From Gauss's Law, we can calculate the electric flux through all the surfaces of the cube, then divide by 6.
Using Symmetry, we can get rid of the intergal for Gauss's Law.
E * A = Qencl / [tex] \epsilon[/tex]
where [tex]\epsilon[/tex] = 8.85*10^-12
Well, the charge is -3.00*10^-6 C
We can divide -3.00*10^-6 C / 8.85*10^-12 F/m
This gets us a flux of 338983.0508 Nm^2
Divide by 6 and we get the flux through one side:
338983/6 = 56497.1Nm^2
I'm not to sure if it's right, but hope this helps!
