You have three cases to calculate and add up.
Here is one: .
You do the other two cases.
Don't forget to add them up.
"Of three urns, the first contains 2 white and 4 black cards, the second contains 8 white and four black cards, and the third contains 1 white and 3 black card. If one card is selected from each urn, find the probability that exactly 2 white cards are drawn"