Solve the all parts of given problem:

Problem: A dog with a mass of 5kg is standing on a float boat so that he is 20 meters from the shore on a calm lake. He walks 8 meters on the deck of the boat toward the shore and then halts. The boat has a mass of 20 kg and one can assume no friction between the boat and the water and that the water is not moving.

Part I: There are no external forces on the dog boat system that can do any work. Gravity cannot do work because the dog and the boat do not change their vertical position. Does the center of mass of the dog and boat change with respect to the shore as the dog walks on the deck of the boat?

Part II: How far does the boat move away from the shore after the dog stops walking?

Part III: After the dog stops walking how far are he from the shore?

I need help to solve the above problem. Thank you.