第一个单独充分是怎么试出来的。。。 音频讲解到这就不说了呃。。

请教

第一个单独充分是怎么试出来的。。。 音频讲解到这就不说了呃。。

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. 为什么不选D，我觉得statement2也sufficient。一元一次方程能求出各10张。