The ratio of the perimeter of the cylinder to the bottom of the cone is 1:2, the volume ratio is 5:6, the height of the cylinder is 20 cm, how many cm is the height of the cone?
圆柱和圆锥底面周长比是1：2，体积比为5：6，圆柱高为20厘米，圆锥高为多少厘米？
<gadget id="calculator">9 / 10</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">20 * (9/10)</gadget>
<output>18</output>

<result>18</result>