please explain step by step

(no use from excel)

11. Dr. David Gonzalez borrows $82,000 at 12 percent interest toward the purchase of a home. His mortgage is for 30 years. a. How much will his annual payments be? b. How much interest will he pay over the life of the loan? c. How much should he be willing to pay to get out of a 12 percent mortgage and into a 10 percent mortgage with 30 years remaining on the mortgage? Assume current interest rates are 10 percent. Carefully consider the time value of money. Disregard taxes