A cylindrical glass, measured from the inside, has a base diameter of 10 cm and a height of 20 cm. First pour some water into the glass, the ratio of the depth of the water to the distance from the water surface to the mouth of the glass is 1:1, and then put a cone, the ratio of the depth of the water to the distance from the water surface to the mouth of the glass is 3:2. Find the volume of the cone.
一个圆柱形玻璃杯，从里面量，底面直径是10厘米，高是20厘米．先往这个玻璃杯里注入一些水，水的深度与水面离杯口的距离比是1：1，再放入一个圆锥，此时水的深度与水面离杯口的距离比是3：2．求圆锥的体积．
<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">20 * (3/5)</gadget>
<output>12</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">12 - 10</gadget>
<output>2</output>

<gadget id="calculator">20 / 2 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.14 * 25 * 2</gadget>
<output>157</output>

<result>157</result>