There are 7 basketball teams at a tournament, each with 5 players. If each player will shake hands once with every other player not on his team, how many handshakes take place?
There will be 6*5 = 30 handshakes with persons who are not members of one's team. Given that we have total 7*5 = 35 players, we get 30*35 handshakes. But each handshake in this pool of h/s is counted twice. Thus, we have to discount and the answer is 30*35/2 = 525, C.