Master Zhang processes 500 parts, and he processes 150 in 3 hours. At this speed, how many hours will it take to process the remaining parts?
张师傅加工500个零件，他3小时加工150个，照这样的速度，剩下零件的还要加工多少小时？
<gadget id="calculator">500 - 150</gadget>
<output>350</output>

<gadget id="calculator">150 / 3</gadget>
<output>50</output>

<gadget id="calculator">350 / 50</gadget>
<output>7</output>

<result>7</result>