I need help;

5 5 points Paxton Dublin is debating the idea of making a greater down payment on his new duplex His first choice is to use a 25-year constant payment foxed rate mortgage (FRM) in the amount of $650,000 at an interest rate of 9%. His second choice is to put another $100.000 down and get a 25-year constant payment FRM in the amount of $550,000 at an interest rate of 8.35%. What is the marginal cost of borrowing this extra $100,000 if he holds the loan for 15 years? 4.94% 5.90% 6.87% 8.08% 10.96% 12.41% 15.37% 18.73%