The angular momentum of a rotating star cluster varies inversely as a square of the radius of the star cluster. A rotating star collapses under the influence of gravitational forces to form a pulsar. The radius of the star after collapse is 1.0X10^-4 times the radius of the cluster before collapse. Find the ratio of the angular momentums (after/before).

could you please explain how to do this. I know it may be easy for you but im having difficulties understanding could you please help thanks