Appellant is a large concern, doing business on a nation-wide scale. In the sale and distribution of its products it establishes dealerships and allots to each dealer a certain territory within which to sell appellant’s machines, attachments and parts. Prior to June 13, 1952, Western Tractor and Equipment Co. (hereinafter “Western”) was distributor of appellant’s products in sixteen counties in the state of Washington. On that date appellant served notice on Western that the dealership was terminated. Three days later the parties to this suit signed a written agreement whereby appellee became appellant’s new distributor in nine of these counties. The written agreement was a uniform one used by appellant with all its distributors and identical in all relevant parts to the agreement appellant previously had with Western. We detail certain of its provisions which are of importance in the .solution of this appeal:

At the time appellant’s agreement with Western was cancelled on June 13, 1952, Western had on hand a considerable quantity of machines, attachments and parts. In addition Western had placed orders with appellant for thirteen additional machines; appellant had accepted all of these orders prior to June 16, 1952 (when appellee became the new distributor) but had made no shipments to Western before that time. During the next eighteen months appellant delivered the thirteen machines to Western and Western sold these machines plus additional machines, attachments and parts from its old inventory to customers in appellee’s territory. Upon learning of this appellee filed claims for territorial infringement fees with appellant. Appellant disallowed these claims on the ground that Western’s distributorship had terminated on June 13, 1952, and therefore Western was not “another distributor” within the terms of the distributorship agreement (paragraphs 5 and 8.1). Appellee did not attempt to press its claims by legal action before October 2, 1957, the date when its distributorship was cancelled by appellant. Thereafter appellee brought an action, alleging that Western was “another distributor” within the terms of the agreement and that appellee was therefore entitled to infringement fees. Appellant denied this and also defended on the grounds that appellee’s claim was barred by paragraphs 9, 10, 29 and 44 of the distributorship agreement and that appellee had waived any legal claim it might have had for these fees. The trial court made the following findings, among others:

Appellant contends that the terms of appellee’s distributorship contract limit recovery of infringement fees to sales by another distributor which was a distributor, had a territory, and was operating under a similar contract at the time this contract was entered into and also at the time the alleged infringing sales were made; therefore, appellant says, since Western’s distributorship and contract were cancelled before the contract with appellee was entered into, Western was not “another distributor” within the terms of paragraphs 5 and 8.1 (supra). Paragraph 3 of the contract defines “another distributor” as “one who purchases the products manufactured and offered for sale by The Manufacturer, for resale under an agreement with The Manufacturer similar to this agreement”. (Emphasis added.) This definition places all emphasis on the time of purchase, not the time of resale. The apparent purpose of the whole infringement arrangement is to compensate the distributor for sales in his territory by another who has acquired the goods involved from the Manufacturer as a distributor (as contrasted with a private individual or firm to whom the Manufacturer might sell directly). It is undisputed that Western was still a distributor at the time that it submitted and appellant accepted the orders involved here, and it is clear that appellant fulfilled these orders as those of a distributor. These actions clearly bring Western within the definition of “another distributor” insofar as these machines, attachments and parts are concerned. The contract may admit of other interpretations, but it is settled law that when two inconsistent interpretations of a contract are advanced the construction which is unfavorable to the drafter shall be adopted. Clise Investment Co. v. Stone, 1932, 168 Wash. 617, 620-621 , 13 P.2d 9, 11 . The district court’s conclusion that Western was “another distributor” for purposes of the infringement provisions is sustained.

Appellant further argues that even though Western be “another distributor”, Western was entitled to have the disputed machines delivered to it under paragraph 39 of the uniform distributorship contract (supra) since they had been “previously sold”, and that paragraph 44 of appellee’s contract makes appellee’s rights subject to these prior rights of Western. Appellant relies on the testimony of Western’s officers, who testified that Western had prior orders from customers for all of the machines involved here. However, these same officers testified that it was customary in this business for prospective customers to place orders with the representatives of several different manufacturers and then purchase from the one who got them a machine first, and that only about half of the machines ordered would actually be sold to the customers for whom they were originally ordered. It is clear that such orders are not sales and that Western had not already “sold” the machines it had ordered from appellant.

Appellant additionally argues that appellee’s recovery is barred by paragraphs 9 and 10 of the distributorship agreement (supra), which provide that appellee is not entitled to receive infringement payments from appellant until appellant has collected same from the infringing distributor. The requirement that appellant make a good faith attempt to collect from the infringing distributor is implicit in these conditions, and appellant admittedly made no attempt whatever to collect from Western for the infringements involved here. We conclude that Western, having purchased these machines, attachments and parts for resale as a distributor and under a distributorship agreement, was bound by that agreement’s restrictions on the resale thereof even though the agreement itself had purportedly been cancelled in the meantime. This interpretation is supported by paragraph 10, which provides that the infringing distributor’s liability is coextensive with the Manufacturer’s liability to the infringed distributor. Since appellant’s failure to collect from Western was due to its own wilful neglect, paragraphs 9 and 10 constitute no bar to appellee’s recovery. See Vance v. Mutual Gold Corp., 1940, 6 Wash.2d 466, 478 , 108 P.2d 799, 805 .

Another argument presented by appellant is that paragraph 29 (supra) of the distributorship agreement makes appellant’s decision that Western was not another distributor absolutely binding even though erroneous. This contention is without merit for several reasons: (1) We read paragraph 29 to provide that appellant shall have the right to determine whether or not an infringement of a distributor’s territory has occurred. Here there was no dispute as to this, the only question being whether the admitted infringement was by “another distributor”. (2) To apply paragraph 29 as appellant urges and thus give one party to the contract power to conclusively interpret the terms of the contract upon which its own liability to the other party depends would be invalid for it would make the contract illusory. A provision thus construed is far different from one giving a disinterested third person, not a party to the contract, power to arbitrate disputes between those who are parties. (3) Appellant’s assistant sales manager testified that appellant made no attempt to get from Western any of the facts relating to the sales involved in the instant case; the evidence thus supports the trial court’s conclusion that appellant did not make a decision under paragraph 29 and that if it did such decision was arbitrary and unreasonable.

Appellant raises the question whether appellee waived any right it may have had to take legal action to enforce its alleged claims. Waiver is an intentional and voluntary relinquishment of a known right. O’Connor v. Tesdale, 1949, 34 Wash.2d 259, 263 , 209 P.2d 274, 276 . It may be manifested by actions, but such actions must be inconsistent with any other intention than to waive. Bowman v. Webster, 1954, 44 Wash.2d 667, 669 , 269 P.2d 960, 961 . The mere fact that the other party is mistakenly led to believe there’s been a waiver is not enough unless that party relies thereon to his detriment, in which case there’s an estoppel. There is no evidence of any detrimental reliance by appellant, so the only question is whether appellee conducted itself in a manner inconsistent with any other intention than to waive.

On September 5, 1952, appellee wrote appellant submitting its claims for infringement fees. On September 11, 1952, appellant replied, denying the claims for the reason hereinbefore stated. On September 29, 1952, appellee again wrote appellant; in this letter appellee set forth in detail why it thought appellant’s position was incorrect and appellee was entitled to recover. This letter was enclosed with another one dated October 8, 1952, in which appellee said its reasons for sending these letters were to establish appellee’s position and to call attention to ambiguities in the Distributorship Sales and Service Agreement which should be corrected. The letter concluded “* * * rather than make a legal issue of this matter, we are attempting to be cooperative and at the same time make known our business position which we believe to be fair and reasonable.” This last paragraph was also quoted in a letter written by appellee’s attorney to one of appellant’s high officials on October 10, 1952; that letter also states, “The matter we discussed on the telephone several days ago has been handled in the manner I told you it would be, and you have no reason to expect any litigation.” Appellee’s attorney testified that in the telephone conversation referred to appellant’s official had said it would be a terrible mistake for a new Caterpillar dealer to start right out suing the parent company, and that he (appellee’s attorney) had replied that appellee wasn’t suing but was protecting its legal rights so far as the claim was concerned.

We fail to see wherein the above quoted letters show a clear intention or for that matter any intention to waive the claims involved. True, the letters state that appellee does not intend to sue at that time, but they in no way imply that appellee is abandoning its claim. This is made even clearer by a subsequent letter from appellee to appellant dated October 15, 1952, later in date than all of the letters discussed above, which sets out in complete formal detail ten claims for infringement fees and asks for “prompt attention to these claims for reimbursement”. Appellee’s failure to sue at any time prior to October 1, 1957, is readily understandable in view of paragraph 38 of the distributorship agreement (which makes it terminable at will by either party) and the implied warning which appellee’s attorney received in his telephone conversation with appellant’s representative. There was no waiver.

The district court awarded appellee interest at the rate of six per cent per annum from the time each of the infringing sales by Western occurred. Appellant assigns this as error. Under Washington law interest is allowed on all claims that are liquidated or readily ascertainable by mathematical computations or by reference to standards prescribed in the contract — in other words where it is not necessary to rely upon opinion or discretion. Mall Tool Co. v. Far West Equipment Co., 1954, 45 Wash.2d 158 , 273 P.2d 652 . The distributorship agreement in the instant case sets forth precise standards for computing the infringement fees on interterritorial sales of machines, attachments and parts, respectively. The number of alleged infringing sales involved and the list price of each appear from the record not to have been contested; the contested issue looming large between the parties was whether Western was “another distributor”. The trial court determined the interest due by the application of fixed standards contained in the contract to the list prices of the goods sold.

Appellant claims that other findings of the trial court are erroneous. All of these assignments of error are either without merit or irrelevant.

Affirmed.