Many tax preparation organizations will prepay customers’ tax refunds if they pay a one-time finance charge. In essence, the customer is borrowing the money (the refund minus the finance charge) from the tax preparer, prepaying the interest (as in a dis-count note), and then repaying the loan with the tax refund. This procedure allows customers access to their tax refund money without having to wait. Joy had a tax refund of $743.21 due. She was able to get her tax refund immediately by paying a finance charge of $39.95. What annual simple interest rate, to the nearest hundredth of a percent, is Joy paying for this loan assuming 

(a) The tax refund check would be available in 5 days? 

(b) The tax refund check would be available in 10 days?

(c) The tax refund check would be available in 20 days?