According to principle of moments

A. If a system of coplanar forces is in equilibrium, then their algebraic sum is zero

B. If a system of coplanar forces is in equilibrium, then the algebraic sum of their moments about any point in their plane is zero

C. The algebraic sum of the moments of any two forces about any point is equal to moment of the resultant about the same point

D. Positive and negative couples can be balanced