Question: A family went out to see a movie. The regular ticket costs $9 and the ticket for children is $2 less. They gave the cashier two $20 bills and they received a $1 change. How many children are there if there are 2 adults in the family? Think carefully first, then make a decision:
They gave the cashier $20 x 2 = $40. Since a $1 change was returned, this means the tickets cost $40 - $1 = $39. Two adult tickets cost $9 x 2 = $18. So, $39 - $18 = $21 was spent for the children's tickets. Each child's ticket costs $9 - $2 = $7. Therefore, there are $21 / $7 = 3 children. So the answer is 3.