4. Michael bought a house for R1425500. He took out a mortgage bond for this amount repayable monthly at an interest rate of 11%% p.a. over 30 years. a) What would the monthly repayment be? b) After 4 years of payments the interest rate changed from 11%% to 10%% p.a. Calculate Michael's new monthly payment. c) What would the outstanding balance on the loan after 15 years? d) Calculate the total amount of interest paid during the first 15 years