On August 31, 2018, you closed on your new condominium and obtained a $300,000, thirty-year mortgage at an APR of 4.2%. The first monthly payment was due at that time (August 31, 2018), and then monthly thereafter (this is an "annuity in advance" or an "annuity due") 8. a. What was the amount of your required monthly payment? Assuming that you made all payments exactly when due, how much interest will you pay on the mortgage in the calendar year ending December 31, 2018? b. c. How much interest would you pay in 2019 if you made all of your scheduled payments exactly when due? If the interest rate were to decrease to 3.6% after seventy-two payments (six years), what would be the amount of your new monthly payment? (the life of the mortgage would be unchanged). d