The actual distance of 150 km is represented on a map by a line segment 3 cm long. The distance between A and B measured on this map is 12 cm. What is the actual distance between A and B in kilometers?
在一幅地图上用3厘米长的线段表示150千米的实际距离．在这幅地图上量得A、B两地的距离是12厘米，A、B两地的实际距离是多少千米．
<gadget id="calculator">150 * 100_000</gadget>
<output>15_000_000</output>

<gadget id="calculator">3 / 15_000_000</gadget>
<output>1/5_000_000 = around 0</output>

<gadget id="calculator">12 / (1/5_000_000) / 100_000</gadget>
<output>600</output>

<result>600</result>