You randomly draw a marble from a bag of marbles that contain seven blue marbles two green marbles and one red marble what is p(not draw a blue marble)

I'm assuming you're asking for probability of not drawing a blue marble. What you need to do is add the 7 blue marbles with the 2 green marbles and the 1 red marble to get 10. This is your denominator. Then you add the green and red to get 3. This is your numerator. So the probability that you will not draw a blue marble is