The master processes a batch of parts at a rate of 60 per hour, which can be completed in 4 hours. If the master is required to finish processing in 3 hours, how many parts should be processed per hour? (Solve with ratio)
师傅加工一批零件，每小时加工60个，4小时就能加工完成．如果要求师傅用3小时加工完，每小时应加工多少个零件？(用比例解)
<gadget id="calculator">60 * 4</gadget>
<output>240</output>

<gadget id="calculator">240 / 3</gadget>
<output>80</output>

<result>80</result>