Answer: 45 months
Explanation:
Credit owed $7200
Monthly payment $225
APR annaully 18.4%
Monthly APR = 18.4/12 = 1.533%
SOLUTION
1st Month interest payment
1.533% x $7200 / 100 = $110.40
Principal paid (monthly payment - interest paid) = $225 - $110.40 = $114.60
Balance ( principal - principal paid) = 7200 - 114.60 = $7085.40
2nd Month interest payment
1.533% x $7085.40 / 100 = $108.64
Principal paid (monthly payment - interest paid) = $225 - $108.64 = $116.36
Balance ( principal - principal paid) = $7085.40 - $116.36 = $6969.04
By following this step up to the 45th month you get $74.74 as the monthly payment this sums up to.
Month interest payment
1.533% x $74.74 / 100 = $1.15
Principal paid (monthly payment - interest paid) = $75.88 - $1.15 = $74.74
Balance ( principal - principal paid) = $74.74 - $74.74 = $0
The payment would be completed at exactly 45months