Two forces are exerted on the crankshaft by the connecting rods. The direction cosines of $F_A$ are $cos\theta_x = -0.182$, $cos\theta_y = 0.818$, and $cos\theta_z = 0.545$, and its magnitude is 4 kN. The direction cosines of $F_B$ are $cos\theta_x = 0.182$, $cos\theta_y = 0.818$, and $cos\theta_z = -0.545$, and its magnitude is 2 kN. What is the sum of the moments of the two forces about the $x$-axis? (This is the moment that causes the crankshaft to rotate.)