TT-29-9

又不懂了……请教NN

A total of 100 customers purchased books at a certain bookstore last week.  If these customers purchased a total of 200 books, how many of the customers purchased only 1 book each?

(1)   None of the customers purchased more than 3 books.

(2)   20 of the customers purchased only 2 books each.

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

答案选c

个人觉得应该选e啊。。谢谢。。

有1 2 列个方程

3x+y=160

x+y=80

直接把有一本书的人求出来了都

选C