Where is the Electric Field Zero on a Line Between Two Charges?

[tjj4h8]

Homework Statement

A 5.0 μC charge is placed at the 0 cm mark of a meter stick and a -4.0 μC charge is placed at the 50
cm mark. At what point on a line joining the two charges is the electric field zero?

Homework Equations

I am not quite sure which equation to use. Do I need to use E=k(q)/r^2?

The Attempt at a Solution

 

[Mindscrape]

Hello, and welcome. Yes, use the standard equation for E. Remember that E works on superposition.