A charge of -3.30 nC amd a charge of -5.40 nC are seperated by a distance of 60 cm. Find the position at which a third charge of +7.

A charge of -3.30 nC amd a charge of -5.40 nC are seperated by a distance of 60 cm. Find the position at which a third charge of +7.10 nC can be placed so that the net electrostatic force on it is zero.