Number of ways in which a lawn-tennis mixed double be made from seven married couples if no husband and wife play in the same set is

We first select 2 men out of 7 in  7C2 ways. Now we exclude the wives of these two selected men and so select2ladies from remaining 5 ladies in  5C2 ways. Let A, B be two men and X, Y be the ladies playing in one set. Then we can have(i) A and X plying against B and Y. (ii) A and Y playing against B and X.Then the total number of ways is  7C2×5C2×2=21×10×2=420