Problem Solving

on a certain day a certain store sold copies of only 2 news paper: P and Q. It sold each copy of P for $1.50 and each copy of Q for $1.75 on that day. Of the total sales of newspaper that day, x percent were copies of Q. Of the total revenue from these sales, y percent was from the sales of Q. Which of the following expresses x in terms of y?

a. 300y/350-y
b. 450y/525-y
c. 600y/700-y
d. 750y/875-y
e. 900y/1050-y

This problem is virtually identical to PS198 in the OG13 (https://www.beatthegmat.com/q-198-ps-gma ... 82646.html).
What is the source?

Architj wrote:on a certain day a certain store sold copies of only 2 news paper: P and Q. It sold each copy of P for $1.50 and each copy of Q for $1.75 on that day. Of the total sales of newspaper that day, x percent were copies of Q. Of the total revenue from these sales, y percent was from the sales of Q. Which of the following expresses x in terms of y?

a. 300y/350-y
b. 450y/525-y
c. 600y/700-y
d. 750y/875-y
e. 900y/1050-y

Since there is a VARIABLE IN THE ANSWERS, we can PLUG IN our own values.

Let y=100, implying that 100% of the total revenue is attributed to sales of Q.
Since Q is responsible for ALL OF THE REVENUE, Q constitutes x=100% of the total sales.

The question stem asks for the value of x=100. This is our target.
Now plug y=100 into the answer choices to see which yields our target of 100.
Only C works:
600y/700-y = (600*100)/(700-100) = 100.

The correct answer is C.