The vertical and horizontal poles at the traffic-light assembly are erected first. Determine the additional force and moment reactions at the base O caused by the addition of the three 100-lb traffic signals B, C, and D. Report your answers as a force magnitude and a moment magnitude.
Sum of all forces and moments =0
The Attempt at a Solution
I got the Force at O right, but the moments im not sure how to sum them
Edit: solved by finding magnitude of M