Question

A rigid L-shaped lever arm is pivoted at point P.

Three forces act on the lever arm, as shown in the diagram.
What is the magnitude of the resultant moment of these forces about point P?

Answer 1

-5(2)-10(2)+15(3)=15

Answer 2

for the moment of forces, you'll have to consider the perpendicular distance form the point of application of force and the axis. in your case, 10N and 5N act counter-clockwise and the 15N acts clockwise. consider clockwise direction to be positive and then find the moments of forces acting and add them up to get the resultant.