Step 1 :The problem is about calculating the downpayment, the amount to borrow, and the monthly payments for a mortgage.
Step 2 :The downpayment is calculated as a percentage of the total cost of the house. In this case, it is 9% of $900000. So, the downpayment is \(0.09 \times 900000 = \$81000.0\).
Step 3 :The amount to borrow is the total cost of the house minus the downpayment. So, the amount to borrow is \(900000 - 81000 = \$819000.0\).
Step 4 :The monthly payments can be calculated using the formula for the monthly payment on a fixed-rate mortgage, which is: \(P = \frac{r \times PV}{1 - (1 + r)^{-n}}\), where P is the monthly payment, r is the monthly interest rate (annual rate divided by 12), PV is the present value, or the amount borrowed, and n is the number of payments, or the term of the loan in months. Substituting the given values, we get the monthly payment as \$5276.83.
Step 5 :Final Answer: \(\boxed{\text{(a) The amount of the downpayment is \$81000.0}}\)
Step 6 :Final Answer: \(\boxed{\text{(b) The amount that Greg and Cheryl plan to borrow is \$819000.0}}\)
Step 7 :Final Answer: \(\boxed{\text{(c) The monthly payments are \$5276.83}}\)