Two identical iron balls are 1 meter apart from each other

Question

Solve the all parts of given question:

Question: Two identical iron balls are 1 meter apart from each other. The volume of the balls is 1 cm³. Suppose someone can move one electron from each atom of ball A and give it to ball B.

Part A: What is the magnitude of the electrostatic force between two iron balls?

Part B: What is the magnitude of the gravitional force between two iron balls?

Part C: How many electrons would need to be transferred in order to balance these two forces?

I know the correct answer for above question but explain how to get this answer! Thanks.