求助一道GWD数学题目，关于percent

Idontcare4u

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)

我的列式：

设总共卖出x件，总共收益R元
则对于A：1.00*(1-p%)x=r%R  
  对于B：1.25*p%x=(1-r%)R.
然后利用x/R=x/R进行联立然后变形后得
  r%=(1-p%)/(0.25p%+1)
之后不知该如何化简才能得到D这样的结果……
还请高人指点！

Idontcare4u

呃……木有人理睬。自己顶一下！

李学子

得到跟楼主相同的结论

Idontcare4u

无奈了……那么就让这厮随风逝去吧！

秋晨小仔

表示这题不会做。。。

Idontcare4u

是……不会化简。。。这种percent的题目都不好做