Two people, A and B, start from two places 30 kilometers apart at the same time and walk towards each other. A walks 6 kilometers per hour, and B walks 4 kilometers per hour. How many hours later will they meet?
甲、乙二人分别从相距30千米的两地同时出发相向而行，甲每小时走6千米，乙每小时走4千米，二人几小时后相遇？
<gadget id="calculator">6 + 4</gadget>
<output>10</output>

<gadget id="calculator">30 / 10</gadget>
<output>3</output>

<result>3</result>