Thank you for posting your question here at brainly. Below is the solution:
To find the circumference (orbit) of an object, you use Pi x Diameter.
As you have the circumference of B, you divide it by Pi to get the Diameter.
So 120 divided by 3.141592654 = 38.2 minutes for the Diameter.
As' radius and Diameter will be 3x greater than B.
38.2 x 3 = 114.6
To get back to the orbital period, times 114.6 by Pi, and you will get 360 minutes.