For any two sets A and B, prove the following:
A ∩ (A’ ∪ B) = A ∩ B
Expanding
(A ∩ A’) ∪ (A∩ B)
(A ∩ A’) =ϕ
⇒ ϕ ∪ (A∩ B)
(A ∪ ϕ =A)
⇒ (A∩ B)