Answer:
Kate starts with 25 marbles. Of these 25 marbles, 10 are green. So the probability of choosing a green marble is 10/25 = 2/5. Since Kate does not replace the green marble, there are 24 marbles left. Of these 24 marbles, 6 are yellow, meaning 18 are not yellow. So the probability of selecting a marble that is not yellow is 18/24 = 3/4. From these probabilities:
P(green, then not yellow) = (2/5)(3/4) = 3/10