How do I solve for the answers in 19 and 21?

19. An electric field of magnitude 5.25 x 10' N/C points due south at a certain location. Find the magnitude and direction of the force on a -6.00 MC charge at this location. Answer X 3.15 N due north 20. V An electron is accelerated by a constant electric field of magnitude 300 N/C. a. Find the acceleration of the electron. b. Use the equations of motion with constant acceleration to find the electron's speed after 1.00 x 10-8 s, assuming it starts from rest. 21. Charge q1 = 1.00 nC is at x1 = 0 and charge 92 = 3.00 nC is at x2 = 2.00 m. At what point between the two charges is the electric field equal to zero? Answer + 0.732 m