Please solve this question on excell and show formulas please.

9. A partially amortizing mortgage is made for $60,000 for a term of 10 years. The borrower and lender agree that a balance of $20,000 will remain and be repaid as a lump sum at that time. a. If the interest rate is 7 percent, what must monthly payments be over the 10 -year period? b. If the borrower chooses to repay the loan after five years instead of at the end of year 10 , what must the loan balance be