Question

In this line of circles

Answer 1

The ratio 1: 3 means there is 1 red one and 3 blue ones.

For the ratio 3:1 there needs to be 3 red for every one blue.

You have 3 blue ones, so you would need 3 x 3 = 9 red ones.

You already have 1 red one so you would need 8 more.