Answer:
First answer: $170 per month
Second answer: 50 months, or 4 years and 2 months
Explanation:
Step 1: Find out how much he paid in the first year. He started with $8500 in debt and after the first year his debt was down to $6460, subtract $6460 from $8500...
$8500 - $6460 = $2040
So he paid $2040 in the first year. Divide that by 12 to see how much he paid per month.
$2040/12 = $170 per month
Step 2: Find out how many months it takes him to pay back the full $8500. Divide $8500 by $170
$8500/$170 = 50
So 50 months, or 4 years and 2 months