If one machine processes 48 parts in 4 hours, how many hours will it take to process 420 parts with 5 such machines? (Solved by comprehensive method)
一台机器4小时加工48个零件，要用5台这样的机器加工420个零件，需要几小时？(用综合法解决)
<gadget id="calculator">48 / 4</gadget>
<output>12</output>

<gadget id="calculator">420 / 12 / 5</gadget>
<output>7</output>

<result>7</result>