I need help with this questions:

7-5 . Baker is an auditor for ABC Company. He is reviewing the expense reports that Green, a salesperson, has submitted over the last twelve months. Baker notices that Green's expenses for "customer development dinners" consistently range between $160 and $170, and the amounts are almost always a round number. ABC Company has a policy that limits reimbursement for business dinners to $175 unless otherwise authorized. In addition, most of the expense reports show that Green paid for the meals in cash, even though he has been issued a company credit card that he usually uses for other travel and entertainment expenses. What kind of expense reimbursement scheme is Green most likely perpetrating, based on these circumstances?

7-6. What internal controls would help prevent an employee from claiming an expense more than once?