Answer:
10
Step-by-step explanation:
Let the people be represented by numbers (1,2,3,4,5)
-- now 1 shakes hands with the remaining 4, (i.e 2,3,4,5)
-- 2 shakes hands with the remaining 3 (i.e 3,4,5) as it has already shaken hands with 1
-- 3 shakes hands with the remaining two and so on
If you recognize the pattern there are 4+3+2+1 handshakes that have taken place, or 10 handshakes