Finding probability yellow M&M came from bag 1 using Bayes

[ParisSpart]

Two bags of M & M chocolates are within:

the first 20% yellow, 20% red and 60% green, and
the second 40% yellow, 40% red and 20% green.
Pull a chocolate M & M from each bag and put them in a container. If at the end of the container contains one yellow and one green chocolate then what is the probability that the yellow came from the first bag?

i must use the type of Bayes : P(A/B)=P(AandB)/P(B) like that
(20/100*20/100*20/100)/(20/100*20/100*20/100+20/100*40/100*40/100) but i don't take the correct answer where i did mistake?

 

[mfb]

How did you get that expression? I would expect different factors, but it is hard to see where you made a mistake without intermediate steps or explanations.