Youyou and Xiaoao run around the circular playground. It is known that the length of the circular track is 400 meters. You first ran for 10 seconds. How long did it take for Xiao Ao to catch up with Youyou for the second time?
优优和小奥绕环形操场跑步，已知环形跑道一圈长400米，优优的速度为4米/秒，小奥的速度为6米/秒，两人站在同一起跑线上同向而跑，优优先跑了10秒．小奥第二次追上优优经过了多长时间？
<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">400 * 1</gadget>
<output>400</output>

<result>400</result>