A train passes a bridge at a speed of 20 meters per second. It takes 1 minute for the train to pass through the bridge completely. The time for the train to be completely on the bridge is 40 seconds. How long is the bridge in meters?
一列火车以20米每秒的速度通过一座大桥，火车从上桥到完全通过用了1分钟时间，火车完全在桥上的时间是40秒钟，请问大桥长多少米？
<gadget id="calculator">20 * 60</gadget>
<output>1_200</output>

<gadget id="calculator">1_200 + 800</gadget>
<output>2_000</output>

<gadget id="calculator">1 + 1</gadget>
<output>2</output>

<gadget id="calculator">2_000 / 2</gadget>
<output>1_000</output>

<result>1_000</result>