Uncle Wang sent tobacco leaves from our village to the county seat. He drove for 3 hours at a speed of 40 km/h, and it took only 2 hours for Uncle Wang to return. How many kilometers per hour did Uncle Wang travel on average when he returned?
王叔叔从我村送烟叶去县城，去时以40千米/时的速度行驶了3小时，返回时王叔叔只用了2小时．王叔叔返回时平均每小时行多少千米？
<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">40 * (3/2)</gadget>
<output>60</output>

<result>60</result>