circular runway is 400 meters long. Xiao Hong and Xiao Ming are walking in the same direction at the same time, Xiao Hong runs 280 meters per minute, and Xiao Ming runs 320 meters per minute. How many minutes later did Xiao Ming meet Xiao Hong for the first time?
一个环形跑道长400米．小红和小明同时同地同向而行，小红每分钟跑280米，小明每分钟跑320米．多少分钟后小明第一次遇到小红？
<gadget id="calculator">320 - 280</gadget>
<output>40</output>

<gadget id="calculator">400 / 40</gadget>
<output>10</output>

<result>10</result>