Please help me with this Algebra question!?

First, add up all the numbers to get the denominator, which would be 20. Than add the amount of green and yellow to get the numerator, which would be 7. The probability that he will pick a green or yellow marble on the first draw is 7/20. For the second draw, you are assuming that one marble has already been picked, so now the denominator will be minus 1, or 19. There are 8 pink marbles so the probability that he will pick a pink marble on the second draw will be 8/19.