A bridge is 1200 meters long, a train passes the bridge at a speed of 20 meters per second, and the length of the train body is 300 meters, how many seconds does it take for the train to get on the bridge and leave?
一座桥长1200米，一列火车以每秒20米的速度通过这座桥，火车车身长300米，则火车从上桥到离开需要多少秒．
<gadget id="calculator">1_200 + 300</gadget>
<output>1_500</output>

<gadget id="calculator">1_500 / 20</gadget>
<output>75</output>

<result>75</result>