Master Zhang needs to produce 120 parts, and 30 parts are produced in 5 hours. According to this calculation, how many hours will it take to complete the task? (Solution with proportional knowledge)
张师傅要生产120个零件，5小时生产了30个，照这样计算，还要多少小时才能完成任务？(用比例知识解)
<gadget id="calculator">120 - 30</gadget>
<output>90</output>

<gadget id="calculator">30 / 5</gadget>
<output>6</output>

<gadget id="calculator">90 / 6</gadget>
<output>15</output>

<result>15</result>