Use the Rule of 78 to Find the Amount of Unearned

Use the Rule of 78 to find the amount of unearned interest for the loan paid in full before the date of maturity.
-Finance charge: $788 Total number of payments: 22
Remaining number of payments, when paid in full: 7

A) $65.41
B) $71.64
C) $95.52
D) $87.21