b. 2/9
You add up how many marbles there are. in this case there is 10. 3 out of those are blue. so you start out with the probability being 3/10. you take 1 marble out, making the total 9 now. now look at the color. you started with 2 red, 3 blue, and 5 yellow. you pulled out a blue, didnt put it back, so now there are 2 blue marbles left out of 9 marbles. there probability is now 2/9. hope i helped you.