想问如何用计算器算这个rate

问题如下：

An issuer is comparing a 12% bank loan with a supplier's terms of 2/10, net 30, paying on day 10. The best decision in terms of the lower cost of financing is to:

选项：

A.

Borrow from the bank to take advantage of the trade credit terms.

B.

Forgo the discount and use the supplier’s financing to pay on day 30.

C.

Use either option as the cost of the bank loan and trade credit are identical.

解释：

A is correct. The cost of the supplier’s trade credit expressed as an effective annual rate (EAR) is 44.59%, which is higher than the 12% interest rate on the bank loan.

B is incorrect because the cost of the supplier’s trade credit is higher than the bank loan rate.

C is incorrect because the bank loan rate of 12% is lower than the effective annual rate of 44.59% on the supplier’s trade credit​​.