Question

let A and B be two sets such that : n(A) = 20, n(AUB) = 42, n(AnB) = 4. Find (1)n(b), (2) n(a-b) (3) n(b-a).
please answer fast guys........​

Answer 1

Answer :-

1. n(B) = n( AUB) - n(A) + n(AnB)

= 42 - 20 + 4

= 26

n(A-B) = n (A ) - n( AnB )

= 20 - 4

= 16

n(B-A) = n (B) - n(AnB)

= 26 - 4

= 22