Master Zhang processes a batch of parts. If he processes 40 parts per hour, the task can be completed in 20 hours; if he processes 50 parts per hour, how many hours can he complete the task?
张师傅加工一批零件，如果每小时加工40个，20小时可以完成任务；如果每小时加工50个，多少小时可以完成任务？
<gadget id="calculator">20 / 50</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">40 * (2/5)</gadget>
<output>16</output>

<result>16</result>