Finding the position of a person walking across a uniform bar on a fulcrum where it first tips

[JohnnyLaws]

Homework Statement

We have a 4-meter-long uniform bar weighing 100 kg, and a person weighing 75 kg is walking across it. The statement specifies a stationary point C situated 2.5 meters away from the origin where the bar can rotate. The question is: 'What distance can this person move away while keeping the bar in equilibrium?'

Relevant Equations

I believe that I should set all torques equal to 0 and forces too but I don't know How to draw this specific Free body Diagram. On the other hand I don't know why I need point C.
So here is my equations:
Ra = reaction in A
Rx = reaction in person
Wb = bar's weight
Wp = Person's weight

Forces:
Ra+Rx+Wb+Wp = 0
Ra+Rx-100-75 = 0

Torques:

0*Ra+x*Rx-2*100-x*75 = 0

I think that explained all in "Relevant equations".
Here is the image of this exercise:

This is my Free Body Diagram:

 

[kuruman]

You have not accounted for all the forces. Doesn't the fulcrum exert a force at point C?
Also, you need an additional equation. What is so special about the point of tipping? In other words what condition must hold for the bar to tip?

 

[Lnewqban]

... but I don't know How to draw this specific Free body Diagram.

Simply represent all the known and unknown possible forces acting on the bar.
For example,
Rx = reaction in person
is a real force, but it is not acting on the bar; therefore, it is not interesting regarding resolving the balance of the beam.

Please, see:
https://courses.lumenlearning.com/suny-osuniversityphysics/chapter/5-7-drawing-free-body-diagrams/

On the other hand I don't know why I need point C.

Please note that:

*The support A only restrains the bar end from moving downwards, but it lets the end go upwards.

*The support C is a pivot, which retrains any movement of the point C, except rotation on the plane of the paper.

*The problem is asking you about the maximum distance that the man can move his weight to the right without inducing the above rorartion.