After visiting several automobile dealerships, Richard selects the car he wants. He likes its $10,500 price, but financing through the dealer is no bargain. He has $2,100 cash for a down payment, so he needs an $8,400 loan. In shopping at several banks for an installment loan, he learns that interest on most automobile loans is quoted at add-on rates. That is, during the life of the loan, interest is paid on the full amount borrowed even though a portion of the principal has been paid back. Richard borrows $8,400 for a period of two years at an add-on interest rate of 10 percent.

a. Total Interest is 1680

b. 12,180

c. 420

d. I need help on D which is below

What is the annual percentage rate (APR)? (Enter your answer as a percent rounded to 2 decimal places.)