You plan to purchase a $150,000 house using a 15-year mortgage obtained from your local credit union. The mortgage rate offered to you is 6 percent. You will make a down payment of 20 percent of the purchase price. a. Calculate your monthly payments on this mortgage. b. Calculate the amount of interest and, separately, principal paid in the 80th payment. c. Calculate the amount of interest and, separately, principal paid in the 120th payment. d. Calculate the amount of interest paid over the life of this mortgage.