At a party , each person shakes hands with every other person . the total number of hand shakes was 66. how many persons are present at the party ?
A 6 b 11 c 12 d 18 e 33
Line up half of the people with the other half of the people facing them.
One line has people, so handshakes can take place.
Each person can shake hands with (x-1) other people,
hence there are handshakes possible
the factors of 132 that differ by 1 are 11 and 12, hence x=12, x-1=11.
12 people are at the party.