Answer:
20 hand shakes
Step-by-step explanation:
person 1 shakes hand with 2 3 4 5 and 6, which equals 5
person 2 shakes hand with 3 4 5 and 6, which equals 4
person 3 shakes hand with 4 5 and 6, which equals 3
person 4 shakes hand with 5 and 6, which equals 2
person 5 shakes hand with 6, which equals 1
person 6 already shook hands with everybody so that equals 5
5+4+3+2+1+5=20