The ratio of the lengths of trains A and B is 4:5, and they are traveling in the same direction. It takes 20 seconds for Xiao Ming on train A to see train B passing by. After how many seconds did it pass the first car?
甲、乙两列火车的长度比是4：5，它们同向而行，在甲车上的小明看到乙车从后向前开过的时间是20秒，那在乙车上的小冬看到经过几秒超过甲车？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">20 * (4/5)</gadget>
<output>16</output>

<result>16</result>