A variable-rate mortgage of $150,000 is amortized over 25 years by equal monthly payments. After 12 months the original interest rate of 6% compounded semi-annually was raised to 6 8% compounded semi-annually. Two years after the mortgage was taken out, it was renewed at the request of the mortgagor at a food rate of 62% compounded semi-annually for a four-year term (a) Calculate the mortgage balance after 12 months (b) Compute the size of the new monthly payment at the 6.8% rate of interest. (c) Determine the mortgage balance at the end of the four-year term (a) The mortgage balance is $after 12 months (Round the final answer to the nearest cont as needed. Round all intermediate values to six decimal places as needed)