Step-by-step explanation:
Step 1:
Calculate trge total amount of monthly repayment over 30 years, we will have
For each month he paid

For 30 years, he will pay

The amoun of the down payment is

Hence,
The amount they ended up paying for the townhome
(including the down payment and monthly payments) will be

Step 2:
To figure out the interst paid on the mortgage, we will substracted the total amount for the townhome from the total repayment including downpayment

Hence,
The interest is
