A bank customer borrowed $10,000, but received y dollars less than this due to discounting. If there was a separate $25 service charge, then, in terms of y, the service charge was what fraction of the amount that the customer received?

答案是25/（10000-y）

可是为什么不是25/（10000-y-25）

理解题吧

个人认为"separate"就是你取多少钱，收对应的费用。一共拿了10000-y元，这就是分母，而25是单独另付给银行的。好比去邮局汇款500元，要另外付500*1%=5元，而不是从500里面扣变成汇495元