The sum of the volumes of two cylinders and cones with the same base and height is 16 cubic decimeters. What is the volume of the cylinder?
两个等底等高的圆柱和圆锥的体积和是16立方分米，圆柱的体积是多少立方分米．
<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<gadget id="calculator">16 / 4</gadget>
<output>4</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<result>12</result>