PREP PS1里的一道题，没人讨论过

我算了几遍，都是E，答案是B，怎么算出来的？

PREP135.
                13701-!-item-!-187;#058&009670

For each of her sales, a saleswoman receives a commission equal to 20 percent of the first $500 of the total amount of the sale, plus 30 percent of the total amount of the sale in excess of $500.  If the total amount of one of her sales was $800, the saleswoman's commission was approximately what percent of the total amount of the sale?

(A) 22%

(B) 24%

(C) 25%

(D) 27%

(500*20%+(800-500)*30%)/800=(100+90)/800=23.75%

23.75%跟24%最接近

又看了一遍题，原来800是total sales，我之前读了三遍都以为800是total commission呢。太粗心了！

多谢楼上的。