Two trains, fast and slow, are running towards each other. The length of the fast train is 50 meters, and the length of the slow train is 80 meters. The speed of the fast train is twice that of the slow train. If it takes 5 seconds for the person sitting in the slow car to see the fast car passing through the window, how many seconds will it take for the person sitting in the fast car to see the slow car passing through the window?
快、慢两列火车相向而行，快车长50米，慢车长80米，快车的速度是慢车的2倍．如果坐在慢车上的人见快车驶过窗口的时间是5秒，那么，坐在快车上的人见慢车驶过窗口的时间是多少秒．
<gadget id="calculator">50 / 5</gadget>
<output>10</output>

<gadget id="calculator">80 / 10</gadget>
<output>8</output>

<result>8</result>