Master Gao made 168 parts in 8 hours, and Master Zhu made 120 parts in 5 hours. How many more parts per hour does Master Zhu make than Gao Zhu? The column comprehensive formula is: how much.
高师傅8小时做168个零件，朱师傅5小时做120个．朱师傅比高朱师平均每小时多做多少个零件？列综合算式是：多少．
<gadget id="calculator">120 / 5</gadget>
<output>24</output>

<gadget id="calculator">168 / 8</gadget>
<output>21</output>

<gadget id="calculator">24 - 21</gadget>
<output>3</output>

<result>3</result>