Two charged particles, q1 = −2.50×10−3 C and q2 = +3.700e-3 C, are separated by a distance of 5.00 cm. (a) What is the electric potential energy of this configuration? (b) What is the electric potential at a point midway between the particles?

I have the answer to a..which is -1.66e6, but I can get the correct answer for b