A bag contains 7 red marbles, 12 orange marbles, 18 yellow marbles, and 5 purple marbles. A marble is drawn at random from the bag.

What is the probability that the marble drawn will not be orange?

First determine the total number of marbles.

7+12+18+5 = 42 total marbles.

Then determine how many are not orange.

42-12 = 30 marbles are not orange

Then divide the number that are not orange by the total number

30/42 = about 70% chance it will not be orange

First you add together all of them to get the denominator. 7+12+18+5 is 42.

then you need to add together the non-oranges or take away the oranges from the total. 42-12 is 30 so the probability to get a marble that is not orange is 30/42

15/21.