Jimmy is selling used books at a yard sale. A customer buys 9 books at a cost of $0.75 each and pays with a $20.00 bill. Jimmy must determine c, the amount of change in dollars he should give the customer. Which equation represents c?

A20 - 0.75c = 9
B20 - 0.75 = 9c
C0.75(9) + c = 20
D0.75c + 9 = 20