On a 400-meter-long circular track, A and B start running in the same direction at the same time. If A runs 320 meters per minute and B runs 300 meters per minute, how long did it take for the two to meet for the first time?
在400米长的环形跑道上，甲、乙两人同时同地同向出发跑步，若甲每分钟跑320米，乙每分钟跑300米，多长时间两人第一次相遇？
<gadget id="calculator">320 - 300</gadget>
<output>20</output>

<gadget id="calculator">400 / 20</gadget>
<output>20</output>

<result>20</result>