You have $3000 in credit card debt with nominal annual interest 18%, compounded monthly. You pay $100 per month except for the last payment which may be less than $100.
(a) How long will it take you to repay the debt, what is the value of the last payment and how much total interest will you pay?
(b) Answer the same question as in (a) assuming you only pay $50 per month.
(c) For what monthly payment, you only pay interest and never finish paying off the full debt?