A & B entered into a binding written contract whereby A promised to hire B as the manager for his health food store for a period of 24 months and B promised to work in the store 8 hours a day, 5 days a week for $800 a week. After two months B comes to A and asks for a S50 a week raise. A orally agrees, provided B promises to work an extra hour on Friday nights. B works 9 hours on Friday for the next month. A refuses to pay B the extra $50 and seeks your advice on his legal rights.
Advise him, making sure to answer these questions: Would evidence of this oral agreement be admissible or in violation of the "parol evidence rule"? Is there a valid legal modification of the contract between A and B? Is the promise of A to pay an additional $50 per week legally enforceable? Explain fully. This is problem from Smith and Roberson Business Law.