On a map with a scale of 1:4000000, the distance between A and B is 20 cm. A train travels from A to B at 160 kilometers per hour. How long does it take?
例尺是1：4000000的地图上，量得A、B两地的距离是20厘米．一列火车从A到B，每小时行160千米，几小时到？
<gadget id="calculator">1 / 4_000_000</gadget>
<output>1/4_000_000 = around 0</output>

<gadget id="calculator">20 / (1/4_000_000) / 100_000 / 160</gadget>
<output>5</output>

<result>5</result>