Vectors in Space · Hard problem

A rigid body is acted on by two forces: $\mathbf F_1 = (4, 0, 3)$ N applied at the point $(0, 2, 0)$, and $\mathbf F_2 = (-4, 1, -3)$ N applied at the point $(1, 0, 2)$ (positions measured from the pivot at the origin). Find the magnitude of the NET torque about the origin.