Question 4-6 with simple work

4. A negative charge of - 4.0 x 10 5 C and a posivite charge of 7.0 x 10- C are separated by 0.15 m. What is the force between the two charges? 5. A negative charge of - 8.0 x 10 6 C exerts an attractive force of 12 N on a second charge that is 0.050 m away. What is the magnitude of the second charge? 6. Two negative charges that are both - 5.0 x 10- C push each other apart with a force of 15 N. How far apart are the two charges