It took Uncle Wang 10 hours to transport goods from Shanghai to Beijing. The speed of the truck was 42 km/h, and it only took 7 hours to return. How many kilometers per hour did the truck travel on average?
王叔叔开车从上海运货到北京用了10小时，货车的速度是42千米/时，返回只用了7小时，货车返回平均每小时行多少千米？
<gadget id="calculator">10 / 7</gadget>
<output>10/7 = around 1.428571</output>

<gadget id="calculator">42 * (10/7)</gadget>
<output>60</output>

<result>60</result>