Finding the distance between two charges

[watabi]

Homework Statement

The potential energy of a system of two charges (q1 = 5.0 µC and q2 = 3.3 µC) is 0.37 J. What is the distance between the charges?

Homework Equations

U=(kq_0q)/r --> r=U/(kq_0q)

U=V/q_0

V=0.37J
q1 = 5.0 µC
q2 = 3.3 µC

The Attempt at a Solution

So I was going to use equation 2 but I have two charges involved and that one only asks for q_0.
Do I calculate the change of the charge and use that for q_0?

 

[LittleMrsMonkey]

V is potential.
U is potential energy.

 

[watabi]

V is potential.
U is potential energy.

Wow, that cleared up a lot so,

r= 0.37J/((8.99e9)(5e-6)(3.3e-6)) ?

 

[LittleMrsMonkey]

Try solving for r again,you've made a mistake.

 

[watabi]

Try solving for r again,you've made a mistake.

Was it the micro?

 

[LittleMrsMonkey]

No.And it's the correct equation.The fraction is mot correct,though.

 

[LittleMrsMonkey]

Seeing it in this form might help you: $U=\frac{q_1q_2}{r}$
So,does $r=\frac{U}{q_1q_2}$?