一道简单道数学题，基本概念

如题，孩子习题里的例题。不难，但标准答案似乎错了——基本概念有误。请大家帮看看。

Ali, Ben, Carol and Dim shared some stickers. Ali received 20% of the stickers. Ben received 16 fewer stickers than Ali. Carol received twice as many stickers as Ben. Dim got the remaining 144 stickers
(a) Find the total number of stickers shared by these four children.
(b) What is the per cent more stickers than Ali did Dim receive?

我的答案：(a) 480, (b) 50%
标准答案(b) 给的是 10%，也就是按全部stickers 算的。　
而且，讲基本概念时，明确说了下面的话：

Given A and B, find the percentage of B more than A.　% B more than A： (B-A)/(A+B) x100%
难道不应该是(B-A)/A x100% 吗？


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