The distance between A and B is 300km. On a map, the distance between the two places is 6cm. On this map, the distance between A and C is 4cm. How many kilometers is the actual distance between A and C?
甲乙两地相距300km，在一幅地图上量得两地相距6cm，在这幅地图上又量得甲丙相距4cm，求甲丙的实际距离是多少千米？
<gadget id="calculator">300 * 100_000</gadget>
<output>30_000_000</output>

<gadget id="calculator">6 / 30_000_000</gadget>
<output>1/5_000_000 = around 0</output>

<gadget id="calculator">4 / (1/5_000_000) / 100_000</gadget>
<output>200</output>

<result>200</result>