Question

Tickets for a school play sold for $7.50 for each adult and $3 for each child the total receipts for the 113 tickets sold were $663 find the number of adult ticket sold

Answer 1

7.5a+3c=663
a+c=113

Write a literal equation for c using the second equation.
c=-a+113

Substitute the value of c into the first equation
7.5a+3(-a+113)= 663
7.5a-3a+339=663
4.5a+339=663
4.5a=324
a=72

Final answer: 72 adult tickets sold

Check by finding the value of c and plugging both values in
(72)+c=113
c=41

7.5(72)+3(41)
663
True