The master made 400 parts in 5 hours, and the apprentice made 240 parts in 4 hours. On average, how many parts did the master make more than the apprentice per hour?
师傅5小时做了400个零件，徒弟4小时做了240个零件，平均每小时师傅比徒弟多做多少个？
<gadget id="calculator">400 / 5</gadget>
<output>80</output>

<gadget id="calculator">240 / 4</gadget>
<output>60</output>

<gadget id="calculator">80 - 60</gadget>
<output>20</output>

<result>20</result>