train is 1320 meters long. When the train passes a bridge, its speed is 980 meters per minute. It takes 4 minutes from the front of the train to the bridge and the rear of the train to leave the bridge. How long is the bridge?
一列火车长1320米，这列火车在通过一座大桥时车速为980米/分，从车头开上桥到车尾离开桥共用了4分钟，这座大桥长多少米？
<gadget id="calculator">980 * 4</gadget>
<output>3_920</output>

<gadget id="calculator">3_920 - 1_320</gadget>
<output>2_600</output>

<result>2_600</result>