A certain one-day seminar consisted of a morning session and an afternoon session.If each of the 128 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 我想选C 想问如果选B，求得的只是一个比例不是具体数字啊 文中的at least 128怎么利用呢？ 谢谢解答！ | 
