Probabilities: "A bag contains counters that are red, blue, green and yellow. There are 9 red, (3x) blue, (x-5) green and (2x) yellow. If the probability of picking a red at random is 9/100, work out the probability of picking a green."
If there is a total of 100 counters, 9 + (3x) + (x-5) + (2x) = 100.
3x + x + 2x = 100 + 5 - 9
6x = 96
x = 16
Probability of picking green = (16 - 5)/100 = 11/100
