Complex sentence: This torque of 1/3 balances the parabola, which is at a distance -1 from the fulcrum, so the area of the parabola must then be 1/3 to give it the opposite torque.
Split into simpler sentences: This torque of 1/3 balances the parabola, which is at a distance -1 from the fulcrum. Hence, the the area of the parabola must be 1/3 to give it the opposite torque.