Know that P(B∣A)=P(B) ⟺ BP(B|A) = P(B) \iff BP(B∣A)=P(B)⟺B and AAA are independent.In this case P(A∩B)=P(A)⋅P(B)P(A ∩ B) = P(A)⋅P(B)P(A∩B)=P(A)⋅P(B).