The master processes 20 parts per hour, and the apprentice processes 12 parts per hour. After they process for the same period of time, the master processes 40 more parts than the apprentice. How many hours did they process?
师傅每小时加工零件20个，徒弟每小时加工零件12个，他们加工相同一段时间后，师傅比徒弟多加工40个零件，他们加工了几小时？
<gadget id="calculator">20 - 12</gadget>
<output>8</output>

<gadget id="calculator">40 / 8</gadget>
<output>5</output>

<result>5</result>