Q30:

Joanna bought only $0.15 stamps and $0.29 stamps.  How many $0.15 stamps did she buy?

(1)   She bought $4.40 worth of stamps.

(2)   She bought an equal number of $0.15 stamps and $0.29 stamps.

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.

为什么答案是D，而不是A。

数学不好，别见笑。

设买了X张价格为0.15的邮票,由(2)可知0.15的和0.29的邮票数量一样多

0.15X+0.29X=4.4 >>>>X=10

所以STATEMENT 2 ALONE IS SUFFICIENT