Betty and John want to buy a house worth $217231. They will qualify for a 20-year mortgage at a 3.3% annual rate as long as their down-payment is 7%...

Betty and John want to buy a house worth $217231. They will qualify for a 20-year mortgage at a 3.3% annual rate as long as their down-payment is 7% of the home's value. If they make the down-payment and take the mortgage for the remaining amount, how much will they pay in interest? 

Assume mortgage payments are made monthly.