In order to find the probability of drawing a marble that is NOT BLUE, we must find the ratio of non-blue marbles to the total amount of marbles
Let's count how many marbles total there are first
8 red + 3 blue + 1 green = 12 marbles total
Now, how many marbles are there that ARE NOT BLUE
8 red + 1 green = 9 marbles THAT ARE NOT BLUE
Now let's create a ratio to find a probility
9/12
This can be simplified to 3/4 by taking out the common factor of 3
Your answer is D! "three-fourths"