请教GWD-7-Q23该如何做，没有头绪

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.

The answer is C

楼主就是没有看懂图, 这个图的意思就是竖的+横的=中间格子里面点, 注意最左上角的 加号

所以: m=d+z, n=e+y...这样就清楚了吧