Calvin Johnson has a

$4,500

debt balance on his Visa card that charges

15.8

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

3

percent of his debt balance, which is

$135.

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

$135

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

4

percent. If Calvin made monthly payments of

$180

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