Paul will be able to save $ 400 per month (which can be used for mortgage payments)

Question:

Paul will be able to save $ 400 per month (which can be used for mortgage payments) for the indefinite future. If Paul finances the remaining cost of the home (after making the $ 20,000 down payment) at a rate of 9% over 30 years, what are his resulting monthly mortgage payments? Can he afford the mortgage?