Uncle Li drove a truck full of fruits from the orchard to the station. The speed was only 45 km/h, and it took 4 hours to reach the train station. When returning empty, it took only 3 hours. How many kilometers per hour did Uncle Li travel on average when he returned?
李叔叔驾驶着一辆装满水果的货车，从果园出发到车站．去时速度只有45千米/时，用了4小时到达火车站．空车返回时，只用了3小时．李叔叔返回时平均每小时行多少千米？
<gadget id="calculator">4 / 3</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">45 * (4/3)</gadget>
<output>60</output>

<result>60</result>