d. Monthly payment: We will use the formula provided with the values: PMT = $66,500(0.10/12) / [1 - (1 + 0.10/12)^(-12*30)] Calculating the PMT will give us the monthly payment amount. e. Total cost of interest over 30 years: Total cost of interest = Total payments over 30 years - Mortgage amount Total cost of interest can be calculated by multiplying the monthly payment by the number of months in 30 years and then subtracting the mortgage amount