Xiaoxiao and grandpa took a walk by the lake. Walking around the lake, Xiaoxiao takes 12 minutes, and Grandpa takes 15 minutes. Now grandpa and Xiaoxiao set off from a small tree by the lake and walk in the opposite direction. As a result, Grandpa met Xiaoxiao 400 meters away from the starting point. At this time, how many meters did Xiaoxiao walk?
笑笑和爷爷在湖边散步．沿着湖走一圈，笑笑要12分钟，爷爷要15分钟．现在爷爷和笑笑从湖边一棵小树旁出发，反方向散步．结果爷爷在离出发点400米处与笑笑相遇．这时，笑笑走了多少米？
<gadget id="calculator">12 / 15</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / (4/5)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">400 * (5/4)</gadget>
<output>500</output>

<result>500</result>