A bag contains 8 blue and 7 yellow marbles. What is the probability of randomly drawing a blue marble and then randomly drawing a yellow without replacing the first marble.

First you want to find out how many marbles you start with so it'd be 8+7=15. You start with 15 marbles. If you randomly drew a blue marble, it'd be 8:15 and if you drew a yellow marble without replacing the blue one, it'd be 7:14 or 50-50 chance.