Answer:
Given: P(A ∩ B) = 0, P(B) = 0.9, P(A ∪ B) = 0.9.
We have: P(A ∪ B) = P(A) + P(B) - P(A ∩ B)
=> 0.9 = P(A) + 0.9 - 0
=> P(A) = 0.9 - 0.9 = 0
Hope this helps!
:)
