Answer:
$110 interest paid
Explanation:
Let's see how much ultimately Susie has to pay.
90 per month for 2 years (2*12 = 24 months) = 90 * 24 = $2160
Also, she made a 50 dollar downpayment, so total paid is:
2160 + 50 = 2210 dollars
Thus, the cost is 2100, but ultimately she has to pay 2210 for using installment plan.
How much interest is that?
The exxtra amount is the interest, so
2210 - 2100 = $110 interest paid