Question

In a suvey of 100 out-patients who reported at a hospital one day it was find out that 70 complained of fever, 50 complained of stomachs and 30 were injured. All 100 patients had at least one of the complains. How many patients had all three complains?

Answer 1

Just add them together
70+30+50=150
150-100=50
50 people had all three