The ratio of the number of teeth of the two alternating large gears to the small gears is 5:4. If there are 30 large gears, how many small gears are there?
两个交互的大齿轮与小齿轮齿数的比是5：4，已知大齿轮有30个，则小齿轮有多少个．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">30 * (4/5)</gadget>
<output>24</output>

<result>24</result>