If A and B are events such that P(A)=1/2, P(B)=1/3 and P(AuB)=2/3. Find P(B'/A)

Question

Anyone know probability, I'm really stuck on this one..... I need help

Answer 1

Draw the Venn diagram. P(A) + P(B) - P(B∩A) = P(A∪B) or 1/2 + 1/3 - P(B∩A) = 2/3

P(intersection) = 5/6 - 2/3 = 1/6

P(B'∩A) = P(A) - P(B∩A) = 1/2 - 1/6 = 1/3 if I understood the problem correctly.