A train with a length of 150 meters passes a railway bridge with a length of 900 meters at a speed of 30 meters per second. Then the total time for the train from the time when the front of the train enters the bridge to the time when the rear of the train exits the bridge is shorter than that of the train completely on the bridge. How long is the time in seconds.
一列长为150米的火车以每秒30米的速度经过一座长为900米的铁路桥，那么火车从车头上桥开始到车尾下桥结束所经历的总时间，比火车完全位于桥上的时间长多少秒．
<gadget id="calculator">150 + 900</gadget>
<output>1_050</output>

<gadget id="calculator">900 - 150</gadget>
<output>750</output>

<gadget id="calculator">1_050 - 750</gadget>
<output>300</output>

<gadget id="calculator">300 / 30</gadget>
<output>10</output>

<result>10</result>