For a road roller, the diameter of the rear wheel is three times the diameter of the front wheel, the rear wheel rolls 3 times, how many times does the front wheel roll
一台压路机，后轮直径是前轮直径的3倍，后轮滚动3圈，前轮滚动多少圈
<gadget id="calculator">3 * 3.14 * 3</gadget>
<output>28.26</output>

<gadget id="calculator">28.26 / 3.14</gadget>
<output>9</output>

<result>9</result>