Sherry and Sam want to purchase a condo on the beach. They will spend $650,000 on the condo and are taking out a loan for the condo for 20 years at 7.0% interest.

a. What is the monthly payment on the mortgage? (2pts) Construct the amortization of the loan for the 20 years in Excel to show the monthly interest costs, the principal reduction, and the ending balance for each month.

b. Then change the amortization to reflect that after 10 years, Sherry and Sam will increase their monthly payment to $7500 per month (7 points for spreadsheet). When will they fully repay the mortgage with this increased payment if they apply all the extra dollars above the original payment to the principal?