When you purchased your house, you took out a 30-year annual-payment mortgage with an interest rate of 5 % per year. The annual payment on the mortgage is $ 17 comma 573. You have just made a payment and have now decided to pay the mortgage off by repaying the outstanding balance. a. What is the payoff amount if you have lived in the house for 18 years (so there are 12 years left on the mortgage)? b. What is the payoff amount if you have lived in the house for 21 years (so there are 9 years left on the mortgage)? c. What is the payoff amount if you have lived in the house for 18 years (so there are 12 years left on the mortgage) and you decide to pay off the mortgage immediately before the 18 th payment is due?