Probability

According to question, P(A) = 0.2, P(AUB) = 0.6 and A and B are independent events.
P(AUB) = P(A) + P(B) - P(AnB) gives, 0.6 = 0.2 +P(B) - P(AnB) gives, P(B) = 0.4 + P(AnB)     ----   (1)
Also, A and B are independent events. Hence, P(AnB) = P(A)*P(B) gives, P(AnB) = 0.2 P(B)     ----   (2)
From (1) and (2) P(B) = 0.4 + 0.2 P(B) gives 0.8 P(B) = 0.4 gives P(B) = 0.5