A cylindrical piece of wood with a length of 12 decimeters is sawed into 3 small pieces of cylinders, and the surface area increases by 20 square decimeters. What is the original volume of this cylindrical piece of wood?
把一根长12分米的圆柱形木料锯成3小段圆柱，表面积增加了20平方分米，这根圆柱形木料原来的体积是多少立方分米？
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">2 * 2</gadget>
<output>4</output>

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

<gadget id="calculator">5 * 12</gadget>
<output>60</output>

<result>60</result>