Observing there is a difference of +8 between each f(x). The slope of this sequence is 8.(y2-y1)/(x2-x1) Using the point slope equation, y-y1 = m(x-x1) yields
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
