The Mustangs have won 4 games and lost in 6.

Then, the probability for winning is 4/10............(1)

The probability of not winning is 6/10

In order to the Mustang to win 6 games, we need to find the number of games the mustang must play in order to won 6 games.

Let the number of games the Mustangs must play be x.

Then the chances to win in 6 games out of the x games must verify the probability mentioned above in (1) which is 4/10

Then, 6/x = 4/10

Now we will cross multiply to find x.

==> 4x = 6*10

==> 4X = 60

==> X = 15

Then, the Mustangs must play 15 games in order to win 6.