Adult tickets & Child tickets

Tickets for a minor league baseball game cost $9 for an adult and $4 for a child. A total of 400 tickets were sold and $3,200 was collected. How many adult tickets were sold and how many children’s tickets were sold? Set up the equations that you need to solve this problem by using this environment. Now make up (and solve) two other similar problems. Explain what makes the new problems similar. Explain how this problem is similar to the ones in the ‘Coin problem’ environment and the ‘Coffee mixture’ environment