On a map with a scale of 1:20000000, the railway distance from A to B is 5cm. Then on the 1:40000000 map, how many centimeters should the railway between A and B be?
在比例尺是1：20000000的地图上，量得甲地至乙地的铁路距离是5cm．那么在1：40000000的地图上，甲、乙两地之间的铁路应有多少厘米？
<gadget id="calculator">1 / 20_000_000</gadget>
<output>1/20_000_000 = around 0</output>

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

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

<gadget id="calculator">100_000_000 * (1/40_000_000)</gadget>
<output>5/2 = around 2.5</output>

<result>5/2 = around 2.5</result>