Jack, a builder, is working on a new set of villas. He hires Bob, a carpenter, on a subcontract to build the wooden frame for the building. The terms of. the agreement are that Bob will complete the work within 4 weeks and will be paid $6000.

During the third week, Bob tells Jack that he is running behind schedule and will not finish the job on time. Jack tells Bob that if he finishes the job on time he will pay him an additional $3000.

Bob finishes the job on time, however Jack refuses to pay him any more than the original $6000 they agreed. Advise Bob whether he has a legal right to the other $3000.

(use the IRAC method and cite the relevant cases in your answer)