Set up help

Question

University Theater sold 506 tickets for a play. Tickets cost $21 per adult and $12 per senior citizen. If total receipts were $7359, how many senior citizen tickets were sold?

Answer 1

let A = number of adult tickets sold; and let S = number of senior citizen tickets sold;  

 

then: A + S = 506 ---------------> 21A + 21S = 21(506) = 10,626

 

and:  21A + 12S = 7359 ------->  21A + 12S = 7359

 

subtracting the bottom equation from the top equation ---> 9S = 3267 ---> S = 3267/9 = 3 ---> S = 363