A train is 400m long and it takes 10 minutes to cross a bridge from the front of the train to the end of the bridge; if its speed increases by 100m per minute, it can pass in 6 minutes. Question: How long is the bridge in meters?
一列火车长400m，通过一座大桥，它从车头上桥到车尾离桥要用10分钟；若它的速度每分钟增加100m，则6分钟即可通过．问：大桥长多少米？
<gadget id="calculator">100 * 6</gadget>
<output>600</output>

<gadget id="calculator">10 - 6</gadget>
<output>4</output>

<gadget id="calculator">600 / 4</gadget>
<output>150</output>

<gadget id="calculator">150 * 10</gadget>
<output>1_500</output>

<gadget id="calculator">1_500 - 400</gadget>
<output>1_100</output>

<result>1_100</result>