Two trains, A and B, are running towards each other at the same time from two places 900 kilometers apart. Train A travels 60 kilometers per hour, and train B travels 30 kilometers more per hour than train A. How many hours later will the two trains meet?
甲、乙两列火车同时从相距900千米的两地相向而行，甲列车每小时行60千米，乙列车比甲列车每小时多行30千米，两列火车几小时后相遇？
<gadget id="calculator">60 + 60 + 30</gadget>
<output>150</output>

<gadget id="calculator">900 / 150</gadget>
<output>6</output>

<result>6</result>