Question

Sets : If n (A − B) = 10 and n (B − A) = 20 and n (A U B) = 45 then find n (A ∩ B).

Answer 1

n (A − B) + n (B − A) + n (A ∩ B) = n(A U B)
10+20+n (A ∩ B) =45
n (A ∩ B) =45-30=15
n (A ∩ B) =15


hope this helps you

Answer 2

n(A-B) + n(B-A) - n(AUB) = n(AnB)
10 + 20 - 45 = n(AnB)
15 = n(AnB)