GMATPrep 里面一条不解的题目

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For each order, a mail-order bookseller charges a fixed processing fee and an additional shipping fee for each book in the order. Rajeev placed five different orders with this bookseller -  an order for 1 book in Jan, an order for 2 books in Feb, an order for 3 books in Mar., an order for 4 books in Apr., and an order for 5 books in May. What's the total of Rajeev's processing and shipping fee for these five orders?

1) Rajeev's processing and shipping fees were $1.00 more for his order in March for his order in Jan.

2) The total of Rajeev's shippin fee for the five orders was $7.50

我选了A，因为根据1）就可以算出来每本book的processing and shipping fix fee = $0 .5, 然后就可以算total了阿。但是大案是E。不知道为什么。请问那位牛人帮忙解释一下？谢谢！！！！

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没有人答复阿？：（

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顶，有没有牛人帮忙答复阿？

Tracylee03

你算出来的是每一本an additional shipping fee for each book 0.5.

正确的计算方法可以写成Y=KX+B (K a fixed processing fee,B是addition shipping fee,X是the number of books.

根据给的条件都只知道X与B的数量,不知道K ,所以无法求出,选E.

猪猪备考

正确的计算方法可以写成Y=KX+B (K a fixed processing fee,B是addition shipping fee,X是the number of books

但是我理解

a fixed processing fee and an additional shipping fee for each book

的意思是：

Y = (K+B)X

怎么理解阿？

taylor1983

两个条件都算不出processing 的

processing  FEE 就是基本的手续费 不是没一本 是以每一个ORDER为单位的