感觉两个条件都不可定，不知道该怎么理解，烦请那位NN帮帮忙，谢过先

The table above shows the results of a survey of 100 voters each responded “favorable” or “unfavorable” or “not sure” when asked about their impressions of candidate M and of candidate N.  What was the number of voters who responded “favorable” for both candidates?

(1)   The number of voters who did not respond “favorable” for either candidate was 40.

(2)     The number of voters who responded “unfavorable” for both candidates was 10.

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.

Answer: A

(1)   The number of voters who did not respond “favorable” for either candidate was 40.

余下60人，要么喜欢M，要么喜欢N，要么都喜欢。30+40=70，70-60=10，所以在喜欢M和喜欢N的人中

有10个人是重合的