A train with a length of 400 meters passes through a tunnel with a length of 2800 meters at a speed of 800 meters per minute. How many minutes does it take for the whole train to pass through?
一列火车长400米，以每分钟800米的速度通过一座长2800米的隧道，全车通过要用多少分钟．
<gadget id="calculator">400 + 2_800</gadget>
<output>3_200</output>

<gadget id="calculator">3_200 / 800</gadget>
<output>4</output>

<result>4</result>