The distance between A and B is 140 kilometers. It takes a car 4.5 hours to drive from A to B, and 5.5 hours to return.
甲乙两地相距140千米，一辆汽车从甲地开往乙地用了4.5小时，返回时用了5.5小时，这辆汽车往返一次平均每小时行多少千米？
<gadget id="calculator">4.5 + 5.5</gadget>
<output>10</output>

<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">140 * (1/5)</gadget>
<output>28</output>

<result>28</result>