The probability of not picking a green is 3/4. To get this answer you would add up the blue and black marbles, giving you an answer of 9. You would then put 9 over 12, which simplified would equal 3/4. Another way to find the answer is to take 1 and subtract 1/4 because 1/4 is the probability of green marbles. Hope this helps!! Have an amazing rest of your day!! :)