We have a purchase at a price of $997.
The downpayment is 10%, so it represents $99.70

Then, the amount that is financed is:

We then can calculate the monthly payments using the annuity formula.
As there are monthly payments, we have to calculate a monthly interest rate:

Then, the monthly payment will be:

We can calculate the total financed payments as:

The finance charge will be the difference between the total financed payments and the financed value:

Answer: Finance charge = $157.50