I agree with Greycellz,
If X is total amount of magazines sold,
Revenue of A = (p/100)*X*1
Hence,
r/100 = (p/100)*X*1 / ((p/100)*X*1 + (1- p/100)*X*1.25)
Simplifications result in D.
Now that looks simple to me now but I was blured for a while on it, is that a difficult level question or not?