On a map with a scale of 1:400000, the linear distance between Beibei's house and grandma's house is 8.5cm. What is the actual linear distance between Beibei's house and grandma's house in km?
在比例尺是1：400000的地图上量得贝贝家与姥姥家的直线距离是8.5cm，贝贝家到姥姥家的实际直线距离是多少km．
<gadget id="calculator">1 / 400_000</gadget>
<output>1/400_000 = around 0.000002</output>

<gadget id="calculator">8.5 / (1/400_000) / 100_000</gadget>
<output>34</output>

<result>34</result>