The lengths of the fast and slow trains are 200 meters and 300 meters respectively, and they travel towards each other. If the person sitting on the slow train sees the express train passing through the window of this person in 8 seconds, how many seconds does it take for the person sitting on the express train to see the slow train passing through the window of this person?
快慢两列火车的长分别是200米、300米，它们相向而行．坐在慢车上的人见快车通过此人窗口的时间是8秒，则坐在快车上的人见慢车通过此人窗口所用的时间是多少秒．
<gadget id="calculator">200 / 8</gadget>
<output>25</output>

<gadget id="calculator">300 / 25</gadget>
<output>12</output>

<result>12</result>