Sergio just purchased a new iPad for $600 using his credit card, which carries an 18% nominal

interest rate. The minimum payment on the card is $25 per month.

a) If Sergio makes the minimum monthly payment and makes no other charges to the card, how

many months will it take him to pay off the balance on his card?

b) If Sergio makes monthly payments of $40, how many months will it take him to pay of the balance

on his card?

c) How much more in payments (dollars) will Sergio make under the $25/month than under the

$40/month plan? What do these extra dollars represent?