请教GWD第五套里的一题目

我的解法是(A纸所卖的钱)/(A纸所卖的钱+B纸所卖的钱)=R/100, 列出的等式是:[ (100-P)/100]/[(100-P)/100+1.25P/100] = R/100

自觉得逻辑不错的,但得不出答案.哪位数学高手指点一下,多谢

Q28:

Last Sunday a certain store sold copies of Newspaper A for $1.00 each and copies of Newspaper B for $1.25 each, and the store sold no other newspapers that day.  If r percent of the store’s revenues from newspaper sales was from Newspaper A and if p percent of the newspapers that the store sold were copies of newspaper B, which of the following expresses r in terms of p?

A.    100p / (125 – p)

B.     150p / (250 – p)

C.     300p / (375 – p)

D.    400p / (500 – p)

E.     500p / (625 – p)

之前做过，记得是D。刚做了下跟lz思路一样，结果解不出了。查了下，我做的题目是...and if p percent of the newspapers that the store sold were copies of newspaper 
                A