The master worker needs to make 480 parts, and 120 parts have been finished. If 90 parts are made every hour, how many hours will it take to finish them all?
工人师傅要做480个零件，已经做完120个，如果每小时做90个，还要几小时能全做完？
<gadget id="calculator">480 - 120</gadget>
<output>360</output>

<gadget id="calculator">360 / 90</gadget>
<output>4</output>

<result>4</result>