请教xdf蓝皮书的一道数学

bluevironikas

A family made a down payment of $75 and borrowed the balance on a set of encyclopedias that cost $400. The balance with interest was paid in 23 monthly payments of $16 each and a final payment of $9. The amount of interest paid was what percent of the amount borrowed?
A 6%  B 12% C 14%  D 16% E 20%
The answer is D

好难念懂。

paopaodong

the amount borrowed=400-75=325

the balance with interest=23×16+9=377

so,interest＝377-325=52

the ratio of interest to the balance=52/325=0.16

missdandan

一家买书需要400块，当时支付了定金75块，余额去借。余额加利息一共付了23个月，再加9块。问支付的利息占借的余额的百分比！

有点搞,关键是利息算不算余额里面，如果算，就是利息也是借的,则52/377=0.1379,没有答案

而52/325正好除尽，好像答案是这个的机会大。

missdandan

 down payment [countable]
a payment you make when you buy something that is only part of the full price, with the rest to be paid later
回楼上：the amount borrowed是不包括利息的，所借本金和需付额度不是同一概念，后者应当只叫做‘payment’吧