The garment factory produces a batch of children's clothing, and produces 500 pieces in the first 4 days, completing 40% of the task. According to this calculation, how many days will it take to complete this task? (Solve with ratio)
服装厂生产一批儿童服装，前4天生产500件，完成了任务的40%，照这样计算，完成这项任务要多少天？(用比例解)
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">4 / (2/5)</gadget>
<output>10</output>

<result>10</result>