Calvin Johnson has a $5,500 debt balance on his Visa card that charges 12.8 percent APR compounded monthly. In 2009, Calvin's minimum monthly payment is 4 percent of his debt balance, which is $220. How many months (round up) will it take Calvin Johnson to pay off his credit card if he pays the current minimum payment of $220 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 $275 at the end of each month, how long would it take to pay off his credit card? a. If Calvin made monthly payments of $220 at the end of each month, how long would it take to pay off his credit card? months (Round up to the nearest unit.)