Tension on the ropes (Equilibrium)

[blackord]

A uniform stage of mass 20kg and length 4m is suspended using 2 ropes as shown in the diagram. A man of mass 80kg is on the stage at a distance of 1.5m from A. Find the tension on the ropes by which the stage hangs...

This is one of my homework questions on equilibrium. The answers are given as 600N & 400N. I'm a newbie... So please explain the answer...

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The Attempt at a Solution

 

[JHamm]

Since there is no movement up or down the sums of tensions pulling up must be equal to the force of gravity pulling down. Also since the platform isn't rotating the net torque about the center of the platform is also zero :)