Well half 1/2 of them are red so you'd have 1/2 the chance of drawing a reed marble scince there are 6 maarbles and 12 marbles in total. Then you'd have a 1/4 chance of drawing a blue marble scine there 12 marbles and 3 blue, You can set it up by counting for example, for the blue, 3,6,9,12, you know you can divide it into 4ths, and so on from there! Good Luck!!!