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 [tex] \frac{3}{10} [/tex]
