Unsure how to find location of force and momento

[low halo]

I understand most of this question, but i dont get how they find the location of the distributed force in each of their working outs, I would appreciate if anyone could give me a hand. Thanks

[languid gorge]

You're summing up all the force in that distributed load (the area of the shape as Nm) and applying that total force at the centroid of the shape that it was applied over:

Your distributed load is a triangle on top of a rectangle. So use the pic above to solve each shape separately, then apply each resultant force in your free body diagram. That's how they got 80 kNm (for the rectangle 20 kN x 4m) applied in the middle of the rectangle shape (2m+2m from A) and for the triangle above it = 10 kN x 4m /2 = 20 kNm applied 1/3L from the left end (so that's 2m + 2/3 4m = 10/3 m from A)

[low halo]

.close Thanks!