If the ratio is 1 divided by 3, Then you need to make a fraction of marbles equal to 1/3. If there are 24 marbles in all, divide this by 4, which equals 6. For every 1 red marble there is 3 blue marbles, which means that if there is 6 red marbles, multiply 6x3 = 18. So there are 6 red marbles and 18 blue marbles. 6/18 is the same as 1/3, so the ratio is correct.
