Mary goes with her 3 children to the circus. Tickets cost $2 for adults and $1 for children. Mary pays with a $20 bill. How much change will she receive?
Let's think step by step below.
15
Mary's ticket costs $2 / ticket * 1 ticket = $2.

Mary's children's tickets cost 3 tickets * $1 = $3.

Together the tickets cost $2 + $3 = $5.

After paying with a 20 - dollar bill, Mary will receive $20 - $5 = $15.

.

So, the answer is 15