Two charges are placed between the plates of a parallel plate capacitor. One charge is $+$q$1$ and the other is q$2=+5\mathrm{.}39$ C$.$ The charge per unit area on each plate has a magnitude of $=1\mathrm{.}23\backslash$times $10-3$ C$/$m$2.$ The force on q$1$ due to q$2$ equals the force on q$1$ due to the electric field of the parallel plate capacitor. What is the distance r between the two charges?