Answer:
(1.) 12
(2.) 20
(3.) 110
Step-by-step explanation: The first answer I'm going to use as an example. Because there is 4 people, one person who is shaking everybody's hands does not count. So we wouldn't count that person making the equation 4x3=12.
If we did add that person we would be basically saying that everyone is shaking their own hands as well as everybody else.
Because there is 4 people and even if you wrote this out on paper and put it out... like
1,2,3,4 showing the number of people and underneath it putting 3 and then adding it all up you would still get 12.