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.

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.

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.

答案：A

问题：为什么不选D呢？条件（2）的话设两种邮票各买了x个，则有：0.15x+0.29x=4.4，解得x=10啊。查看答疑

问题：老师为什么c不成立还是没有听懂为什么a单独就可以解出来查看答疑

问题：C不行么？查看答疑