Two people start from two places 171 kilometers apart at the same time. A rides a bicycle and travels 15 kilometers per hour, and B travels 42 kilometers per hour by car. How many hours can they meet?
两人从相距171千米的两地同时出发，甲骑自行车每小时行15千米，乙乘汽车每小时行42千米，两人几小时可以相遇？
<gadget id="calculator">15 + 42</gadget>
<output>57</output>

<gadget id="calculator">171 / 57</gadget>
<output>3</output>

<result>3</result>