prep数学，大牛给看看

A certain one-day semina consited of a morning session and an afternoon session. If each of the 128 people attending the semina attended at least one of the two sessions, how many of the people attended the morning session only?

1)3/4 of the people attended both sessions

2）7/8 of the people attended the afternoon session

感觉选B吧？  但是答案好像是D

依靠2）是可以推出来的。

7/8 of the people attended the afternoon session，因此1/8的人仅仅去了晨会。

题目问的是仅仅去上午场多少人。

7/8 of the people attended the afternoon session + each of the 128 people attending the semina attended at least one of the two sessions

可以直接推出1/8的人只去了上午场。