Determine the annual percentage interest cost for each of the following terms of sales, assuming the firm does not take the cash discount but pays on the final day of the net period (assume a 365-day year)
a. 1/20, net 30 ($500 invoice)
b. 2/30, net 60 ($1,000 invoice)
c. 2/5, net 10 ($100 invoice)
d. 3/10, net 30 ($250 invoice)