5. (Mortgage restructuring) An investor purchased a small apartment building for $250,000. She made a down payment of $50,000 and financed the balance with a 30- year, fixed-rate mortgage at 12% annual interest, compounded monthly. For exactly 20 years she has made equal-sized monthly payments as required by the terms of the loan. Now she has the opportunity to restructure the mortgage by refinancing the balance. She could borrow the current balance, pay off the original loan, and assume a new loan for the balance. (No points or any other charges are involved in the transaction.) The new loan is a 20-year, fixed-rate loan at 9%, compounded monthly, to be paid in equal monthly install- ments. Suppose she has a risk-free savings account that pays 5%, compounded monthly. Should she restructure the mortgage