You have two kinds of coins, call them coinA and coinB. Twenty of these coins are coinB coins. CoinA coins are worth $0.15 each. Altogether, your coins are worth $5.60. How much is a single coinB worth?
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 one in the ‘Adult tickets and Child tickets’ environment and the ‘Coffee mixture’ environment
Can you represent this problem in the {number of coins, $} plane ? How do the graphs differ?