Consider the following problem: A 30-year mortgage is taken out for $240,000 at an annual interest rate of 6.125%. (a) Implement a function in Excel to compute the value R of the monthly payment and another function to compute the total interest paid over the lifetime of the mortgage. The formulas should take as inputs the amount borrowell, the interest rate; and the number of years. (b) Determine the values of R and total interest under each of the following separate changes (relative to the initial set-up). Create a new row of excel data (and formulas) in each case. (i) The amount borrowed is $340,000. (ii) The interest rate is 5.75%. (iii) The time is 20 years.