How long does it take for a train with a total length of 400m to pass through a 2.8Km long tunnel at a speed of 40Km/h?
一列火车全长400m，以40Km/h的速度通过一条长2.8Km的隧道，需要多少时间？
<gadget id="calculator">0.4 + 2.8</gadget>
<output>3.2</output>

<gadget id="calculator">3.2 / 40</gadget>
<output>0.08</output>

<result>0.08</result>