Physics question help ASAP PLEASE !!!!!!

y 4. Two identical charges of q = - 1.0 x 10-6 C, are placed on the y - axis, 1.00 m from the origin. One sits above, the other below 1.00 m the origin as shown. A third charge is placed on the x - axis, 0.50 0.50 m m from the origin. X a) Calculate the value of this third charge which causes the potential, V, at the origin to be zero. 1.00 m b) What is the electric field at the origin