Question

If 30 people shake hands for another how many handshakes are possible

Answer 1

answer is 30 because if one shake hand for another another will shake for him

Answer 2

formula for number of handshakes in a group of n people

$= \frac{n(n - 1)}{2} \\ here \: n = 30 \\ = \frac{30 \times 29}{2} \\ = \frac{870}{2} \\ = 435$

therefore If 30 people shake hands for another 435 handshakes are possible