Question 53760
A+S=720  THEN A=720-S & 2.50A+1.50S=1220 OR SUBSTITUTING 720-S FOR A WE GET

2.50(720-S)+1.50S=1220 OR 1800-2.50S+1.50S=1220 OR -S=-580 OR S=580 STUDENT TICKETS SOLD. THEN THERE ARE 720-580=140 ADULT TICKETS SOLD.

PROOF 2.50*140+1.50*580=1220 OR 350+870=1220 OR 1220=1220