The railway between A and B is 840 kilometers long. A passenger train departs from A at 8 am and arrives at B at 3 pm. How many miles does the train travel per hour?
甲乙两城的铁路长840千米，一列客车于上午8时从甲城出发，下午3时到达乙城．这列火车每小时行多少千米．
<gadget id="calculator">15 - 8</gadget>
<output>7</output>

<gadget id="calculator">840 / 7</gadget>
<output>120</output>

<result>120</result>