Question

If n(A)=8 and n(A intersection B)=2, then n((A intersection B)´ intersection A is equal to​

Answer 1

n(A∪B)=n(A)+n(B)−n(A∩B)  

Here we are given with

n(A)=7,n(B)=5,n(A∪B)=11

Substitute these values in the above formula.

11=7+5−n(A∩B)

⟹n(A∩B)=12−11=1

∴n(A∩B)=1