Use the Rule of 78 to Find the Payoff Amount

Use the Rule of 78 to find the payoff amount for the loan paid in full before the date of maturity.
-Finance charge: $800 Total number of payments: 46
Amount per payment: $100
Remaining number of payments, when paid in full: 7

A) $784.46
B) $779.28
C) $679.28
D) $684.46