Answer: 0.27
The events are independent, so we can multiply the probabilities.
P(A n B) = P(A) * P(B)
P(A n B) = 0.3 * 0.9
P(A n B) = 0.27
note: The 'n' represents the "intersection symbol", aka "horseshoe" or "upside down U".
The intersection of two events is like asking when the two events will occur simultaneously. Example: If A represents the event "it rains" and B represents the event "a person won a contest" then P(A n B) represents the probability of it raining and the person winning the contest.