On a map with a scale of 1:3000000, the distance between A and B is 50cm. If two buses depart from A and B at the same time and meet each other after 10 hours, it is known that bus A travels every hour. 80km, how many kilometers per hour does bus B travel?
在比例尺是1：3000000的地图上，量得A、B两地间的距离是50cm，如果两辆客车同时从A、B两地相对开出，经过10小时相遇，已知甲客车每小时行驶80km，乙客车每小时行驶多少千米？
<gadget id="calculator">1 / 3_000_000</gadget>
<output>1/3_000_000 = around 0</output>

<gadget id="calculator">50 / (1/3_000_000) / 100_000 / 10</gadget>
<output>150</output>

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

<result>70</result>