Piotr receives an invoice for $10,150.00. The terms of the invoice are 2/7 net 20 . If he doesn't pay the discounted amount on day 7 but pays the ful amount on day 20 , what is the effective simple interest rate their supplier is charging them? Use the daycount convention ACT/365. a. 57,873% b. 57.300% c. 59.019% d. 63,603% e. 55.008%