Okay, here we have this:
Considering the provided information we obtain the following:
Mortgage capital=$170,000
Total payment = Monthly payment * 12 months of the year * number of years
Total payment = $939*12*30
Total payment = $338,040
Total payment = Mortgage capital + Interest
Replacing we obtain:
Total payment = Mortgage capital + Interest
$338,040=$170,000+interest
Interest= $338,040-$170,000
Total Interest=$168,040
Finally we obtain that the total interest is $168040.