In this line of, the ratio of red circles to blue circles is 1:3, How many more red circles would need to be added to make the ratio of red to blue 3:1

8 more red circles because if you have 9 red circles and 3 blue ones the ratio would be 9:3 and if you simplify that down to 3:1 that's the answer. So you would need to add 8 more red circles