On a map with a scale of 1:5,000,000, the distance from Lanzhou to a certain place is measured to be 20 cm. If it is to be drawn on a map with a scale of 1:8,000,000, how long should it be drawn?
在比例尺为1：5000000的地图上，量得兰州到某地的距离是20厘米，如果要画在比例尺为1：8000000的地图上，应画多长？
<gadget id="calculator">1 / 5_000_000</gadget>
<output>1/5_000_000 = around 0</output>

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

<gadget id="calculator">1 / 8_000_000</gadget>
<output>1/8_000_000 = around 0</output>

<gadget id="calculator">100_000_000 * (1/8_000_000)</gadget>
<output>25/2 = around 12.5</output>

<result>25/2 = around 12.5</result>