Electromagnetism static charge and forces

[The black vegetable]

Hi
Everyone, I'm trying to justify to myself why

|F(a)| > |F(b)| > |F(c)|

I think I can see why

|F(b)| > |F(c)|

due to special relativity case c observed from
the charges point of view would observe
the charges closer due to lorentz
contraction. As the charge is invariant would
result in a greater force?

However I can't justify to myself why
|F(a)| > |F(b)|

many thanks

 

[A.T.]

would observe the charges closer due to lorentz contraction.

In which direction is the contraction?

 

[The black vegetable]

Please ignore my justification, I see now it's wrongIm Just trying to find out why

|F(a)| > |F(b)| > |F(c)|

I know that |F(a)| and |F(c)| have the same
electric force independent of motion and that the weaker force
experienced by |F(c)| is a result magnetic attraction

but can't see why
|F(a)| > |F(b)|

I'm new to electromagnetism

many thanks