On a map, the actual distance of 400 km is represented by a line segment of 2 cm. On this map, the distance between A and B is 5 cm. What is the actual distance in kilometers between A and B?
在一幅地图上，用2cm的线段表示实际距离400km，在这幅地图上，量得甲乙两地相距5cm．甲乙两地的实际距离是多少千米？
<gadget id="calculator">400 * 100_000</gadget>
<output>40_000_000</output>

<gadget id="calculator">2 / 40_000_000</gadget>
<output>1/20_000_000 = around 0</output>

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

<result>1_000</result>