求助Taotao math5 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)

答案是D,求解题思路,谢.