A machine tool factory plans to assemble 240 machine tools in 12 days, but actually assembles 30 machines a day. How many days can the task be completed in advance?
某机床厂计划12天装配机床240台，实际每天装配30台，可以提前几天完成任务？
<gadget id="calculator">240 / 30</gadget>
<output>8</output>

<gadget id="calculator">12 - 8</gadget>
<output>4</output>

<result>4</result>