<human>:  Frankie and Carla played 30 games of ping pong against each other. Frankie won half as many games as did Carla. How many games did Carla win?
<bot>: Define a variable ** Let x be the number of games that Frankie won.
How many games did Carla win? ** Then the number of games Carla won would be 2*x.
Write an equation ** And the sum of all the games would be x+2*x=30 games.
Simplify ** Thus, the expression simplifies to 3*x=30.
Divide by 3 ** And the value of x=<<10=10>>10 games.
How many games did Carla win? ** Therefore, the number of Carla's wins would be 2x=20 games.
#### 20