Sonya uses her credit card to pay for new exhaust system that ended up totaling $831.75. She can pay off up to $300 a month. The card has an annual rate of 20.5%. How much will she pay in interest?

Question

anonymous · Answer

I'm not sure about this one, but I'll try to help..
First get the monthly rate:
$$20.5\div12$$ = 1.7083% a month

For $831.75 she obviously had to pay for 3 months if monthly rate is 1.7083%
So $831.75 contains:
Price + 3*monthly rate

$831.75 = 105.125%
So she paid interest of $40.54