A and B are 4 cm long on a map with a scale of 1:20000000. The distance between B and C is 500 kilometers. How long should they be drawn on this map?
甲乙两地在比例尺是1：20000000的地图上长4厘米，乙丙两地相距500千米，画在这幅地图上，应画多长？
<gadget id="calculator">1 / 20_000_000</gadget>
<output>1/20_000_000 = around 0</output>

<gadget id="calculator">500 * 100_000 * (1/20_000_000)</gadget>
<output>5/2 = around 2.5</output>

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