Using 5 point charges, finding the charge of q1 and q2 using given force

[MissJewels]

Homework Statement

The figure shows five point charges placed on a line, at intervals of 1 cm. For what values of q1 and q2resultant electrical force exerted on each of the three charges is zero?

Homework Equations

I imagine the law of coulomb is used here, however, I'm not sure how I'm supposed to tackle this one, since the resulting force on the given charges is zero. I guess, it gets confusing when you add more than 2 charges. Anyway, anyone have any hints to help me figure this one out?

The Attempt at a Solution

Haven't got an idea

 

[Clever-Name]

It's the same as adding 2 forces except now you're adding 4!

Think about what direction each force is acting on and draw some pictures. You know that the total force = 0. In other words. The forces acting to the left have to cancel out the forces acting to the right.