When you purchased your house, you took out a 30-year annual-payment mortgage with an interest rate of 6% per year. The annual payment on the mortgage is $12,000. You have just made a payment and have now decided to pay the mortgage off by repaying the outstanding balance. What is the payoff amount if

a. You have lived in the house for 12 years (so there are 18 years left on the mortgage)?

b. You have lived in the house for 20 years (so there are 10 years left on the mortgage)?

c. You have lived in the house for 12 years (so there are 18 years left on the mortgage) and you decide to pay off the mortgage immediately before the twelfth payment is due?