In a survey of the 100 out-patients who reported at the hospital one day , it was found out that 70 complained of fever, 50 complained of stomach ache and 30 were injured.All 100 patients had at least one of the complaints and 44 had exactly two of the complaints.How many patients had all three complaints?

Answer 1

If x had two complaints,
70+50+20 - 44 + x = 100
Review 3-part Venn diagrams.