Greatest common factor of 20 and 40

Circle a has center of (2,3) and a radius of 5 and circle b has a center of (1,4) and a radius of 10. what steps will show that circle a is similar to circle b 1) dilate circle a by a scale factor of 2 2) translate circle a using the rule (x+1,y-1) 3) rotate circle a 180 degrees about the center 4) reflect circle a over the y-axis