It took 55 seconds for a train to cross a 1400 meter long bridge and 80 seconds for a train to cross a 2100 meter long tunnel. What's the speed and length of the train? Using equation

If the vehicle length is x, then:
（1400+X）/55=（2100+X）/80
X=140
Speed: (1400 + 140) / 55 = 28 (M / s) or (2100 + 140) / 80 = 28 (M / s)

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