\displaystyle \mathbf{M}_O = (– a \cdot P + 2a \cdot 3P – 4a \cdot P) \mathbf{e_z} = aP \mathbf{e_z}
\displaystyle \mathbf{F} = (– P +3P – P)\, \mathbf{e}_y = P\,\mathbf{e}_y
