A couple has $7,750 in credit card debt at 18% nominal rate per year (i.e., 1.5% per month). They could take a 10% down loan instead of a 20% down loan thus use the extra money to pay off the credit-card debt. There are two 15-year loans. Assuming that the market value of their property is $100,000, what is the marginal internal rate of return of switching from Loan 2 to Loan 1? Loan 1: 90% loan with 10% down payment is 6% and 2.5 points; Loan 2: 80% loan with 20% down is 5% and no points