On a map with a scale of 1:30000000, the distance between Shanghai and Beijing is 4 cm. A plane departs from Shanghai and flies 500 kilometers per hour. How long does it take to arrive in Beijing?
在比例尺为1：30000000的地图上，量得上海至北京的距离是4厘米．一架飞机从上海出发，每小时飞行500千米，几小时可以到达北京？
<gadget id="calculator">1 / 30_000_000</gadget>
<output>1/30_000_000 = around 0</output>

<gadget id="calculator">4 / (1/30_000_000) / 100_000 / 500</gadget>
<output>12/5 = around 2.4</output>

<result>12/5 = around 2.4</result>