Three interlocking gears, when A rotates 6 times, B rotates 10 times; when B rotates 25 times, C rotates 9 times. If A has 30 gears, how many gears does C have?
三个互相咬合的齿轮，当A转6圈时，B转10圈；当B转25圈时，C转9圈．如果A有30个齿轮，C有多少个齿轮？
<gadget id="calculator">6 / 10</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">30 * (3/5)</gadget>
<output>18</output>

<gadget id="calculator">25 / 9</gadget>
<output>25/9 = around 2.777778</output>

<gadget id="calculator">18 * (25/9)</gadget>
<output>50</output>

<result>50</result>