It takes a train 180 meters long to cross a bridge at a speed of 15 meters per second in 60 seconds. How many meters is the bridge long?
一列火车长180米，以每秒15米的速度通过一座大桥用了60秒．大桥长多少米？
<gadget id="calculator">15 * 60</gadget>
<output>900</output>

<gadget id="calculator">900 - 180</gadget>
<output>720</output>

<result>720</result>