Roban Electronics was formed in January 2013 and had an initial staff of 15 workers. At a staff meeting at the end of May 2013, the owner of Roban Electronics told the staff that the company might not survive because it was using outdated equipment, and that it was likely that Roban would merge with another firm. The owner asked the employees to stay working for Roban if that happened, and promised the employees that the original 15 workers would each receive 2% of the value of the sale or merger as a reward for staying. In September 2017, Roban was bought by another firm, and the eight workers who were original employees that stayed sought to collect their 2% of the value of the sale. The company refused to pay on the grounds that there was no contract. Would this be a unilateral or bilateral contract? Would this contract be valid and enforceable? List the four elements of a valid, enforceable contract and explain how each element was or was not fulfilled by these facts.