A train is 150 meters long and travels 20 meters per second. How many seconds does it take for the whole car to pass through a 450-meter-long bridge?
一列火车长150米，每秒行20米．全车通过一座450米长的大桥，需要多少秒．
<gadget id="calculator">150 + 450</gadget>
<output>600</output>

<gadget id="calculator">600 / 20</gadget>
<output>30</output>

<result>30</result>