Two trains depart from places A and B which are 2,800 kilometers apart at the same time, and meet each other 7 hours later. Car A travels 250 kilometers per hour, how many kilometers per hour does Car B travel?
两列火车分别从相距2800千米的甲乙两地同时相对开出，7小时后相遇．甲车每小时行250千米，乙车每小时行多少千米？
<gadget id="calculator">2_800 / 7</gadget>
<output>400</output>

<gadget id="calculator">400 - 250</gadget>
<output>150</output>

<result>150</result>