Question

If n(A∪B) = 40, n(A-B)=12 and n(A′∩B)=20, then find n(A∩B).

Answer 1

Given,

n(AUB)=40, n(A-B)=12, n(A'∩B)=20 =>n(B)=20

n(A∪B)=n(A)+n(B)−n(A∩B)

40=12+20-(A∩B)

n(A∩B)=32