An electricity and magnetism problem by Dhruv Patel

It has been experimentally observed that the electric field in a larger region of the earth's atmosphere is directed vertically down.; at an altitude of $300\text{ m}$ , the electric field is $60\text{ V/m}$ . At an altitude of $200 \text{ m}$ ,the field is $100\text{ V/m}$ . Calculate the net amount of charge contained in a cube $100 \text{ m}$ on edge located between 200 mtrs and 300 mtrs altitude.