Question 588432
Let P(A) = x


P(A or B) = P(A) + P(B) - P(A and B)


0.3 = x + 0.5 - 0.6


0.3 = x - 0.1


0.3 + 0.1 = x 


0.4 = x 


x = 0.4



So P(A) = 0.4