Problem:
At one of George Washington's parties, each man shook hands with everyone except his spouse, and no handshakes took place between women. If married couples attended, how many handshakes were there among these people?
Answer Choices:
A.
B.
C.
D.
E.
Solution:
If all people shook hands there would be handshakes. Of these, would take place between women and between spouses. Therefore there were handshakes.