The number of games played is 9
Let the number of games played = g
Amount of bet per game = $2
Number of games won by Marty = 4
Number of games won by Wendy will be;
Amount won by Wendy = $10
This means ;
cost per bet × number of games won by Wendy = 10
2(g - 4) = 10
2g - 8 = 10
2g = 18
g = 9
Hence, They played 9 games.