Conditional Probability with a Ball Chosen From a Random Urn

I have 10 Urns; 9 contain 2 White and 2 Black Balls, one urn contains 5 White and one Black ball. A ball chosen from a random urn is white. What is the probability that it came from the urn with the five white balls?

I know I have to use Bayes Theorem here, but I am not quite sure how to use it in this given case. Any help is highly appreciated.

Thanks, Daniel

Bayes theorem says that: $$P(A|B)P(B)=P(B|A)P(A)$$ let $A$ be the event of the urn you draw from having 5 white balls, and $B$ be the event 'draw a white ball'. Now, you want $P(A|B)$, and this can be expressed in the other three probabilities, which are easier to calculate.