On a 1:50000000 map, the distance between two airports A and B is measured to be 4cm. How long does it take for a civil airliner to fly from airport A to airport B at a speed of 500km per hour?
在一幅1：50000000的地图上，量得甲乙两个机场之间的距离是4cm，一架民航客机以每时500km的速度从甲机场飞往乙机场，需要飞行多长时间？
<gadget id="calculator">1 / 50_000_000</gadget>
<output>1/50_000_000 = around 0</output>

<gadget id="calculator">4 / (1/50_000_000) / 100_000 / 500</gadget>
<output>4</output>

<result>4</result>