To find the cost of each game Bowled by Terry and Tommy, we need to determine the rate of change or the cost per game.
For Terry:
- Total cost = $22.50
- Number of games = 3
The cost per game for Terry is calculated as follows: \[ \text{Cost per game} = \frac{\text{Total cost}}{\text{Number of games}} = \frac{22.50}{3} = 7.50 \]
For Tommy:
- Total cost = $15
- Number of games = 2
The cost per game for Tommy is calculated as follows: \[ \text{Cost per game} = \frac{\text{Total cost}}{\text{Number of games}} = \frac{15}{2} = 7.50 \]
Both Terry and Tommy paid $7.50 per game.
So, the rate of change, or the cost of each game, is: \[ \boxed{7.50} \] per game.