Answer:
Use this formula to answer
u = npV/100+V
u = unearned interest
p = monthly payment
n = number of remaining monthly payments
V = the value from the APR table that corresponds to the annual percentage of loan rate for the number of remaining payments
it should look like this
Example:
n= 12 months, p = 5000, u = 9 months , V = 0.015%
They know their unearned interest/interest(u) already.
n = 36(?)(or 35 if she didn't pay the 12th month and only has for 11) months,
p = $647.02
V = 9%
you can possibly calculate u