A man X has 7 friends, 4 of them are ladies and 3 are men. His wife Y also has 7 friends, 3 of them are ladies and 4 are men.Assume X and Y have no common friends.Then the total number of ways in which
X and Y together can throw a party
inviting 3 ladies and 3 men, so that 3 friends of each of X and Y are in this party, is :
