Question

b.n (A)=20, n(B)=28 n( AUB )=56 then nA intersection B),​

Answer 1

n(A)=20

n(B)=28

n(AUB)=56

n(A intersection B)=?

n(AUB)=n(A)+n(B) - n(A ∩ B)

=>56=20+28-n ∩ B)

=>56=48-n(A ∩ B)

=>48-n(A ∩ B)=56

=>-n(A ∩ B)=56-48

=>n(A ∩ B)= -8

Thank you