Three negative point charges lie along the y-axis. The first charge, q1 = -4.00 nC, lies at y = 10.00cm. The second charge, q2 = -1.00 nC, lies at the origin. The third charge, q3 = -4.00 nC, lies at y =-10.00 cm. What is the electric field at point P that lies on the x-axis at x=8.00 cm?