The distance between A and B cities is 640 kilometers. A car departs from A at 9:00 a.m. for B and arrives at 5:00 p.m. How many kilometers per hour does the car travel on average?
甲乙两城相距640千米，一辆汽车上午9点，从甲城出发开往乙城，下午5点到达，这辆车平均每小时行多少千米？
<gadget id="calculator">17 - 9</gadget>
<output>8</output>

<gadget id="calculator">640 / 8</gadget>
<output>80</output>

<result>80</result>