A 20dm long cuboid is sawed into 3 sections on average, and the surface area increases by 28dm**2. What is the original volume of this cuboid?
把一根长为20dm的长方体木料平均锯成3段，表面积增加了28dm**2，原来这根长方体木料的体积是多少？
<gadget id="calculator">28 / 4</gadget>
<output>7</output>

<gadget id="calculator">7 * 20</gadget>
<output>140</output>

<result>140</result>