Task #$7($Mortgage$).$ In the mortgage example, given in class $($Unit $3,$ slides $57-59)$ we calculated the monthly payment. You might be interested which part of this payment is interest and which part is repayment of the debt. Use a spreadsheet to calculate the interest payment, repayment of principal and the loan balance for every month. Draw a graph that shows nicely how the share of interest decreases over time while the share of repayment increases.