This is a question that needs a bit of common sense to get to the actual answer that is desired. Firstly there is one information given .The other information has to be found from common sense. ! single handshake requires 2 people. Now we can easily determine the number of people doing 66 handshakes.
Then
The number of people required for 1 hand shake = 2
Then
The number of people required to do 66 handshakes = ( 2 * 66) people
= 132 people
Then it can be said that there were 132 people in the party. I hope the process of doing this problem is clear to you.
She would have to pay $30.53
24x.6=1.44
24+1.44=25.44
25.44/.2=5.088
25.44+5.09 (you had to round it up because it's money)
Which equals 30.53
I hoped this helped :)