A passenger plane flies from city A to city B at 10:30 in the morning, and arrives in city B at 2:30 in the afternoon. It is known that the distance between the two cities of A and B is 3960 kilometers. How many kilometers does this passenger plane fly on average per hour?
一架客机上午10：30从A城飞往B城，下午2：30到达B城，已知AB两城间的距离是3960千米，问这架客机平均每小时飞行多少千米？
<gadget id="calculator">3_960 / 4</gadget>
<output>990</output>

<result>990</result>