Each person who attended a certain concert paid the same price for a ticket. How many people attended the concert?
A) If the ticket price had been $6 more and 100 fewer people had attended the concert, the total revenues from ticket sales would have been the same.
B) If the ticket price had been $6 less and 100 more people had attended the concert, the total revenues from ticket sales would have been $1200 less.

[spoiler]OA is C
But I am getting the same two variable equation from both A and B. [/spoiler]