The total length of the bridge is 1200 meters, and the total length of the train is 300 meters. A train travels on a bridge at a speed of 20 meters per second. How many seconds does it take for the train to get on and off the bridge?
大桥全长1200米，火车全长300米．火车以每秒20米的速度在桥上行驶，火车从上桥到离桥需要多少秒钟．
<gadget id="calculator">1_200 + 300</gadget>
<output>1_500</output>

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

<result>75</result>