Consider an equilateral triangle of charges. There is a charge of size +6.5 nC at location (-a/2, 0). There is a charge of size -6.5 nC at location (+a/2, 0).

There is a third electric field at the origin, in N/C. Use k = 9 x 109 N m2 / C2. ( The square root is just over the three).