[求助]关于机经的197题

nicoling

197.
                The question is about students attending three clubs: swimming, coaching and archery

the students who attend swimming also attendMingLiU","serif"; mso-fareast-font-family: 宋体; mso-ansi-language: DE; mso-ascii-font-family: Arial; mso-bidi-font-family: Arial;"> coaching.

16 attend coaching, 9 attend S andMingLiU","serif"; mso-fareast-font-family: 宋体; mso-ansi-language: DE; mso-ascii-font-family: Arial; mso-bidi-font-family: Arial;"> A, and 4 attend three clubs

how many attend both clubs?MingLiU","serif"; mso-fareast-font-family: 宋体; mso-ansi-language: DE; mso-ascii-font-family: Arial; mso-bidi-font-family: Arial;"> 

17

题目说参加S的都参加了C，下面说9个参加了S和A，那么不就是S交C交A为9个吗？，为什么后面又说有4个参加了三项。怎么理解呢？

must700

我也觉得是。

你这个是做哪个版本的呀？ 我正在做的里面没找到这个题。