Deborah borrowed $3,200. She financed it with a 48-month
installment loan with fixed payments of $72.25 per month. Instead
of making her 12th payment, Deborah decided to pay off the balance
of her loan early. (a) what is the APR of the installment loan? (b)
how much interest is saved by paying off the loan early using the
actuarial method? (c) how much must Deborah pay to satisfy the
loan?