Let's denote the circle with small radius circle A and the circle with bigger radius as circle B. In order to perform the translation, you should follow these steps
1) Draw a vector from point A to B
2)Dilate circle A to circle B. It means translating mapping circle A to circle B.
3)By this way, we can claim that circles A and B are similar.
And the similarity ratio is [tex] \frac{ r_{2} }{ r_{1} } = \frac{6}{2} =3[/tex]