For leather shoes produced by a shoe factory, the ratio of the double number produced in October to the double number produced in September is 5:4. 3000 pairs were produced in October, how many pairs were produced in September?
鞋厂生产的皮鞋，十月份生产双数与九月份生产双数的比是5：4．十月份生产了3000双，九月份生产了多少双？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">3_000 * (4/5)</gadget>
<output>2_400</output>

<result>2_400</result>