The point charges in Figure are located at the corners of an equilateral triangle 25.0 cm on a side, where qb = +20.0 μC and qc = -7.00 μC. (Assume that the +x-axis is directed to the right.)
(a) Find the electric field at the location of qa.
(b) What is the force on qa, given that qa = +1.50 nC?