A train is 800 meters long, and it takes 2 minutes to pass a big tree on the side of the road; it takes 5 minutes to pass a bridge at the same speed, how long is the bridge?
一列火车长800米，它通过路边的一棵大树用了2分钟；它用同样的速度通过一座大桥用了5分钟，这座大桥长多少米．
<gadget id="calculator">800 / 2</gadget>
<output>400</output>

<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">400 * 3</gadget>
<output>1_200</output>

<result>1_200</result>