Q30:

The table above shows the number of students in a certain high school class who are boys and the number of students in the class who are studying biology. What is the total number of students in the class?

(1) Of the boys in the class, 15 are studying biology.

(2) The number of girls in the class is twice the number of students in the class who are not studying biology.

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.

继续上题，按照Ｂ的意思，可以设number of girls 为x, 则number not

studying biology 为x/2

因为26+x/2=18+x,这样就可以求出答案了．难道不行吗，为什么要选C呢？