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?
Select.
A) 100p/(125-p)
B) 150p/(250-p)
C) 300p(375-p)
D) 400p(500-p)
E) 500p/(625-p)
This problem can be easily solved by picking numbers. The explanation given in the OG can be very laborious.   Lets say the number of newspaper A sold = 20, so revenue from A = 20 and the number of newspaper sold from B = 80, so revenue from B = 100. Now total revenue =120 out of which 20 came from A. So   r = 20/120 = 1/6 = 16.7% and p = 20   A) 100*20/(125-20) -&gt; Incorrect   B) 150*20/(250-20) -&gt; Incorrect   C) 300*20/(375-20) -&gt; Incorrect   400p(500-p)) 400*20/(500-20) = 8/48 = 1/6*100 = 16.7% - &gt; Correct   E) 500*20/(625-20) -&gt; Incorrect   So Ans 400p(500-p)
<result>D</result>
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?