A friend owes $10,000 on his credit card. He plans to stop making charges and pay off the balance. The card has a minimum payment of 5%. He figures correctly that 5% of $10,000 is $500. From that he concludes that he needs to make the 5% minimum payment for only 20 months, because 20 x $500= $10,000. Is your friend right? If not, explain the error in his reasoning.