A $12,000 car loan has payments of $398.57 per month for three years. What is the interest rate?

A $12,000 car loan has payments of $398.57 per month for three years. What is the interest rate? Assume monthly compounding and give the answer in terms of an annual rate. Round the answer to the nearest whole percentage.

Joe Ferro’s uncle is going to give him $250 a month for the next two years starting today. If Joe banks every payment in an account paying 8.4% compounded monthly, how much will he have at the end of three years? Round the answer to 2 decimal places.