PLS HELP I DON’T UNDERSTAND

The question asks for the probability that a marble is NOT YELLOW
Total Marbles: orange+yellow+blue=7+3+2=12
We need to count all marbles except yellow:
orange+blue=7+2=9
Now to find the probability that is NOT YELLOW:
[tex]\frac{All Marbles Except Yellow}{Total Marbles}[/tex]= [tex]\frac{9}{12} = \frac{3}{4}[/tex]
Answer is 3/4
Hope it helps!