Calvin Johnson has a

$4,500

debt balance on his Visa card that charges

17.8

percent APR compounded monthly. In 2009, Calvin's minimum monthly payment is

4

percent of his debt balance, which is

$180.

How many months (round up) will it take Calvin Johnson to pay off his credit card if he pays the current minimum payment of

$180

at the end of each month? In 2010, as the result of a federal mandate, the minimum monthly payment on credit cards rose to

5

percent. If Calvin made monthly payments of

$225

at the end of each month, how long would it take to pay off his credit card?