Let the no. of papers be A and B.

p= A/(A+B)*100 =>100/p=1+B/A

r= A/(A+1.25B)*100=>100/r=1+1.25B/A

100/r=1+1.25B/A=1+1.25(100/p-1)

100/r=(125-0.25p)/p

r=100p/(125-0.25p) which is the same as D

gluon wrote:

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 A, 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)