Question

At the end of a meeting all participants shook hands with each other. Twenty-eight handshakes were exchanged. How many people were at the meeting?

Answer 1

@Albert0898 Assume that there were x people there
and there were y handskakes
and everybody in the meeting handshakes with everyone BUT him
so \[x(x-1)=y\]
but this count that everyone shakes twice
\[\frac{x(x-1)}{2}=y\]
\[x^2 - x-56=0\]
\[x=8 ,-7 \]
but (-7) is rejected
so the answer will be 8 people