Billy has a credit card with a current balance of $3,500 and a 16% APR. With his current monthly payment, he will be able to pay off this debt in 15 months. But Billy just learned that he is getting a raise at work. If he puts all of the extra income from his raise into his monthly credit card payment, how much additional monthly income would he require from his raise to pay off the credit card in 12 months?
a.
$58.57
b.
$171.37
c.
$258.99