solve the system of equations below by using elimination

Question

the school play is charging $4 for student tickets and $5 for adult tickets. The school earns $500 selling a total of 120 tickets. How many tickets were sold to students

Answer 1

4s +5a = 500

s+a =120

4s +4a = 480

a = 20 adult tickets

s =120-a = 120-20 = 100 student tickets