Uncle Wang set off from the county to deliver fertilizers. It took 3 hours to go, driving 40 kilometers per hour, and 2 hours to return. How many kilometers did he travel per hour when he returned?
王叔叔从县城出发去送化肥，去的时候用了3小时，每小时行驶40千米，返回时用了2小时，返回时每小时行了多少千米？
<gadget id="calculator">40 / 2</gadget>
<output>20</output>

<gadget id="calculator">3 * 20</gadget>
<output>60</output>

<result>60</result>