(a) 20% of $224,000 is $44,800.
(b) 3 points on a $224,000 mortgage is $6,720.
(c) $44,800 + $6,720 is $51,520. So the total down payment and closing costs are $51,520.
(d) The mortgage amount is $224,000 - $51,520 = $172,480.
(e)
Monthly payment = $172,480 * (7%/12%)(30 years) = $1,234.15
Total interest paid over 30 years = $172,480 * 7% * 30 years = $243,720