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(Annuity payments) Calvin Johnson has a $6,000 debt balance on his Visa card that charges 12.2 percent APR compounded monthly in 2009 . Calvin's minimum monthly payment is 3 percent of his debt balance, which is $180. How many months (round up) will it take Calvin Johnson to pay oft 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 4 percent. If Calvin made monthly payments of $240 at the end of each month, how long would if take to pay oft his credit card? a. If Calvin made monthly payments of $180 at the end of each month, how long would it take to pay off his credit card? months (Round up to the nearest unit)