After a 4-meter-long cuboid is sawn into two pieces, the surface area increases by 10 square meters compared to the original one. What is the original volume of the cuboid in cubic meters?
把一根长4米的长方体锯成两段后，表面积比原来增加了10平方米，这块长方体木块原来的体积是多少立方米．
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<result>20</result>