A truck drives from A to B, travels 54 kilometers per hour, arrives in 5 hours, and only takes 4 hours to return along the original road. How many kilometers per hour does the truck travel on average for a round trip?
一辆货车从甲地开往乙地，去时每小时行54千米，5小时到达，沿原路返回时只用了4小时．这辆货车往返一趟平均每小时行多少千米．
<gadget id="calculator">5 + 4</gadget>
<output>9</output>

<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">54 * 5 * (2/9)</gadget>
<output>60</output>

<result>60</result>