Yarou went to deliver books to Meifan, in order to save time, the two left home at the same time. The distance between the two places is 840 meters. Yarou walked an average of 63 meters per minute, and Meifan walked an average of 57 meters per minute. How many minutes later did they meet?
雅柔去给美凡送书，为了节省时间，两人同时从家出发．两地相距840米．雅柔平均每分钟走63米，美凡平均每分钟走57米，几分钟后两人相遇？
<gadget id="calculator">63 + 57</gadget>
<output>120</output>

<gadget id="calculator">840 / 120</gadget>
<output>7</output>

<result>7</result>