Question 22
Some persons in a party shake hands with each other. The following information is known.
- Each person shakes hands with exactly 20 persons.
- For each pair of persons who shake hands with each other, there is exactly 1 other person who shake hands with both of them.
- For each pair of persons who do not shake hands with each other, there are exactly 6 other persons who shake hands with both of them.
Determine the number of persons in the party.
- Each person shakes hands with exactly 20 persons.
- For each pair of persons who shake hands with each other, there is exactly 1 other person who shake hands with both of them.
- For each pair of persons who do not shake hands with each other, there are exactly 6 other persons who shake hands with both of them.
Determine the number of persons in the party.