Answer:
$3,378.35
Explanation
Before we can get the interest, we need to get the amount after 60 60months
A = P(1+r)^t
A = 18000(1+0.035)^5
A = 18000(1.035^5)
A = 18000(1.1877)
A = $21,378.35
Interest = Amount - Principal
Interest = 21,378.35- 18000
Interest = $3,378.35
Hence he will be paying $3,378.35 as interest