The figure shows a rectangular array of charged particles fixed in place, with distance a = 39.2 cm and the charges shown as integer multiples of q1

The figure shows a rectangular array of charged particles fixed in place, with distance a = 39.2 cm and the charges shown as integer multiples of q1 = 3.33 pC and q2 = 5.78 pC. With V= 0 at infinity, what is the net electric potential at the rectangle's center?