There are 120 bricks in a box . the bricks are red blue or green. there are 1/3 red bricks . 1/4 blue bricks

what you need to do is take 1/4 of 120 and 1/3 of 120, this(respectively) is 30 and 40. that means there are 40 red bricks and 30 blue bricks. If you are asking how many red or blue bricks, that's the answer. If you want green bricks(as an example) you just add 30 and 40 and subtract that number(70) from 120, getting 50 green bricks.

Hope this helps! Try to be more specific about the question in the future.