Mitsui Bank hired Ross Duncan as a branch manager in one of its Southern California locations. At thattime, Duncan received an employee handbook informing him that Mitsui would review his performanceand salary level annually. In 2018, Mitsui decided to create a new lending program to help financiallytroubled businesses stay afloat. It promoted Duncan to be the credit development officer (CDO) and gavehim a written compensation plan. Duncan's compensation was to be based on the new program's successand involved a bonus and commissions based on new loans and sales volume. The written plan alsostated, "This compensation plan will be reviewed and potentially amended after one year and will besubject to such review and amendment annually thereafter." Duncan's efforts as CDO were successful,and the business-lending program he developed grew to represent 25 percent of Mitsui's business in 2019and 40 percent by 2020. Nevertheless, Mitsui refused to give Duncan a raise in 2019. Mitsui alsoamended Duncan's compensation plan to significantly reduce his compensation and to change hisperformance evaluation schedule to every six months. When he had still not received a raise by 2020,Duncan resigned as CDO and filed a lawsuit claiming breach of contract. Using the information presentedin the chapter, answer the following questions.

1. What are the four requirements of a valid?

2. Did Duncan have a valid contract with Mitsui for employment as a credit development officer? If so, was it a bilateral or a unilateral contract?

3. What are the requirements of an implied contract?

4. Can Duncan establish an implied contract based on the employee manual or the written compensation plan? Why or why not?