@Sonam
The value of dearrangement is 9 rt.
But after that whyare you calculating 9C2.
Dearrangement gives the number of ways set of teams can be formed satisfying the above condition.
For example if males are (M1,M2,M3,M4) and women are (W1,W2,W3,W4)
Then 1 way to form a set of teams is {(M1,W2),(M2,W3),(M3,W4),(M4,W1)}
Another way to form set of teams is {(M1,W3),(M2,W4),(M3,W1),(M4,W2)}
In this way we can have 9 sets of teams.