PREP模考时碰到的一个数学，迷糊

barrios

A certain one-day seminar consisted of a morning session and an afternoon session. If each of the 128 people attending the seminar 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.

答案是b.statement 2 alone is sufficient, but statement 1 alone is not sufficient.不明白为啥选这个，请教各位nn

小小胖子

only morning + both morning and afternoon + only after=total

attended the after=both morning and afternoon + only after

可求出only morning占1/8;总人数已知，可求得how many

barrios

谢谢小胖啊，晕，其实这是个送分题啊，怎么还范糊涂，考场上希望不要糊涂了，哈