Xiao Ming and Xiao Li start from home at the same time and walk toward each other. Xiao Li walks 50 meters per minute, and Xiao Ming walks 70 meters per minute. When they met, Xiao Ming walked 140 meters further than Xiao Li. How many meters were there between Xiao Ming and Xiao Li?
小明和小莉同时从家出发相向而行，小莉每分钟走50米，小明每分钟走70米．相遇时小明比小莉多走了140米，小明和小莉两家相距多少米？
<gadget id="calculator">70 - 50</gadget>
<output>20</output>

<gadget id="calculator">140 / 20</gadget>
<output>7</output>

<gadget id="calculator">70 + 50</gadget>
<output>120</output>

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

<result>840</result>