On March 1, Computer Programs, Inc. (CP) orally agreed with Holiday Department Store (HDS) to write a set of programs for HDS's computer and to coordinate the programs with HDS's billing methods. A subsequent memo, signed by both parties, provided in its entirety: HDS will pay CP $20,000 in two equal installments within one month of completion if CP is successful in shortening by one-half the 17 processing time for the financial transactions now handled on HDS's Zenon 747 computer; CP to complete by July 1. This agreement may be amended only by a signed writing. On June 6, CP demanded $10,000, saying the job was one-half done. After HDS denied liability, the parties orally agreed that HDS should deposit $20,000 in escrow, pending completion to the satisfaction of HDS's computer systems manager. The escrow deposit was thereupon made. On July 5, CP completed the programs, having used an amount of time in which it could have earned $18,000 had it devoted that time to other jobs. Tests by CP and HDS's computer systems manager then showed that the computer programs, not being perfectly coordinated with HDS's billing methods, cut processing time by only 47 percent. They would, however, save HDS $12,000 a year. Further, if HDS would spend $5,000 to change its invoice preparation methods, as recommended by CP, the programs would cut processing time by a total of 58 percent, saving HDS another $8,000 a year. HDS's computer systems manager refused in good faith to certify satisfactory completion. HDS asked the escrow agent to return the $20,000 and asserted that nothing was owed to CP even though HDS continued to use the programs"If CP in fact had half-completed the job on June 6, would it then have been entitled to $10,000?
Yes, because June 6 was within one month of completion.  Yes, because CP had done one-half the job.  No, because of a constructive condition precedent requiring at least substantial completion of the work before HDS would have a duty to pay  No, because "within one month of completion" would, in these circumstances, be interpreted to mean "within one month after completion."