GWD 27-15

Q15:

The figure above shows two entries, indicated by m and n, in an addition table.  What is the value of n + m?

(1)
              d + y = -3

(2)
              e + z = 12

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.

NN 请解释一下？ 谢谢

正确，答案为C

如图:m=d+z,n=e+y

条件1：
                d + y = -3，不能得出m+n的值  

条件2：e + z = 12，也不能得出m+n的值  

联立1，2可得m+n