The distance between A and B is 280 kilometers, and a truck is scheduled to arrive at B in 8 hours. When the truck travels half the distance, if it stops for half an hour for some reason, if it arrives at point B according to the scheduled time, how many kilometers should it travel per hour?
甲乙两地相距280千米，一辆卡车预定8小时到达乙地．卡车行驶一半路程时，因故停车半小时，如按预定时间到乙地，那么每小时应多行多少千米？
<gadget id="calculator">280 / 2</gadget>
<output>140</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 - 0.5</gadget>
<output>3.5</output>

<gadget id="calculator">140 / 3.5</gadget>
<output>40</output>

<gadget id="calculator">280 / 8</gadget>
<output>35</output>

<gadget id="calculator">40 - 35</gadget>
<output>5</output>

<result>5</result>