The distance between Xiao Ming's house and Xiao Hong's house is 840m. The two start from home at the same time. Xiao Ming walks 70 meters per minute, and Xiao Hong walks 50 meters per minute. How many minutes after the two meet?
小明家到小红家的路程是840m，两人同时从家里出发，小明步行70米/分，小红步行50米/分，两人出发后几分钟相遇？
<gadget id="calculator">70 + 50</gadget>
<output>120</output>

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

<result>7</result>