On a map with a scale of 1:4000000, the distance between A and B is 30 centimeters. Two trains depart from A and B at the same time and meet after 8 hours. Train A travels 80 kilometers per hour. m, how many kilometers does train B travel per hour?
在一幅比例尺为1：4000000的地图上，量得甲、乙两地的距离是30厘米，两列火车同时从甲乙两地相对开出，8小时后相遇，甲列火车每小时行驶80千米，乙列火车每小时行驶多少千米？
<gadget id="calculator">1 / 4_000_000</gadget>
<output>1/4_000_000 = around 0</output>

<gadget id="calculator">30 / (1/4_000_000) / 100_000 / 8</gadget>
<output>150</output>

<gadget id="calculator">150 - 80</gadget>
<output>70</output>

<result>70</result>