Hello, I need help with defining the equilibrium for both moments and force. I need someone to explain it to me$.$ I have my system as the standard right$-$hand rule.

The square steel plate has a mass per unit volume of $6250k\frac{g}{m^3}$ and rests in a

horizontal position, hung from a hook. The thickness of the plate is $50$ mm $.$

My coordinates are:

A $=(1\mathrm{.}2,-1\mathrm{.}2,0)$

B $=(1\mathrm{.}2,1\mathrm{.}2,0)$

C $=(-1\mathrm{.}2,0,0)$

D $=(0,0,2\mathrm{.}4)$

G $($origin$)=(0,0,0)$