aurobindo wrote:

I solved it this way:

A is priced at $1, and sold 50 papers of A. Total revenue from selling A is $50.

B is priced at $1.25, and sold 40 papers of B. Total revenue from selling B is $ 50.

Lets assume that the store sold only A and B. Total revenue by selling A and B is $ 100.

That way r is 50%, and p is 500/9.

Then substituted p's value in all the options. D gave back 50% and is the answer.

I used algebra... quite lengthy for a Gmat question... same result as yours...

For A = number of A newspapers sold; similarly for B:

r/100 = A / (A + 1,25B)

p/100 = A / (A + B)

First, one finds A/B for each equation:

A/B = 1,25r / (100 - r)

A/B = p / (100 - p)

Equating both expressions to the right:

r = 400p / (500 - p) => D.

kripalkavi, could you please tell us the origin (

Kaplan, OG, etc) of the question?