Question 992576
A has a radius of 5, and 5x2= a diameter of 10.
B has a diameter 3 times bigger, so 3x10= a diameter of 30 And 30/2= radius 15.
So, the distance of center A to center B, assuming that the circles are externally tangential, is 20. Look at the drawing I made you.*[illustration Tangent_Circles]