Another Moment Question

I just realized this is in the wrong place..Move it to intro to physics please. Sorry

1. Homework Statement
Using Cartesian vector analysis determine the moment of the three forces about the base of the column at A. F1 =400i +300j+120k

2. Homework Equations

The $$x$$ represents "cross"..i dont know the latex for it

$$M_a = r x F$$ (summation)

3. The Attempt at a Solution

I keep getting the wrong answer and I think it has something to do with the point E. What does this have to do with anything?

What I am doing is summing all the forces crossed with their distances.

$$r_B={12k}N$$
$$r_{F3}={0i-j+8k}N$$

So $$M_A = (r_B x F_1) + (r_B x F_2) + (r_{F3} x F_3)$$

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