University Theater sold 556 tickets for a play. Tickets cost $22 per adult

and $12 per senior citizen. If total receipts were $8492, how many senior

citizen tickets were sold?

Let A be number of adult tickets brought

Let S be number of senior citizen tickets brought

8492 = 22A + 12S (1)

A = 556 - S (2)

Plug (2) into (1)

8492 = 22 (556 - S) + 12S

8492 = 12232 - 22S + 12S

8492 - 12232 = - 22S + 12S

-3740 = - 10S

-3740/10 = - 10S/-10

374 = S

S = 374

Note that there are several more steps you can take to check the answer and/or find A.