Question

let A and B be two sets such that n(A)=20, and find n(B)+ n(A-B) + n(B-A)​

Answer 1

Answer:

(A∪B)=n(A)+n(B)−n(A∩B)

n(B)=42−20+4=26

n(A−B)=n(A)−n(A∩B)=20−4=16

n(B−A)=n(B)−n(A∩B)=26−4=22