Question

Let U be a universal set with subsets A and B such that n(U)=118, n(A)=57, n(B′)=69, and n(A∩B)=11. Find the following:

Answer 1

$n(B)=n(U)-n(B')=118-69=49\\ n(A\cup B)=n(A)+n(B)-n(A\cap B)=57+49-11=95\\ n((A\cap B)')=n(U)-n(A\cap B)=118-11=107$