Two point charges are located along the x axis. q1= +6.0 uC at x1 = +4 cm and q2 = +6uC at x2= -4 cm. Two other charges are located on the y axis q3 = +3 uC at y3=+5cm and q4= -8 uC at y4=+7 cm. Find the net electric field ( magnitude and direction) at the origion.