It takes 40 seconds for a train to cross the 530 meter cave and 30 seconds for a train to cross the 380 meter bridge at the same speed What's the speed of this train? How long is its body?

It takes 40 seconds for a train to cross the 530 meter cave and 30 seconds for a train to cross the 380 meter bridge at the same speed What's the speed of this train? How long is its body?

The train is x meters per minute and Y meters long
There are
40x=530+y
30x=380+y
10x=（530+y）-（380+y）=150
So x = 15
y=70
So the speed is 15 meters per minute, and the body length is 70 meters

It takes 40 seconds for a train to pass through a 530 meter tunnel and 30 seconds to pass through a 380 meter bridge at the same speed

(530-380) / (40-30) × 40-530 = 150 ／ 10 × 40-530, = 600-530, = 70 (m); (530-380) / (40-30); = 150 ／ 10, = 15 (s); a: the length of this train is 70 meters, and the speed is 15 meters

It takes 55 seconds for a train to pass the 800 meter long bridge (from the front of the train to the rear of the train to leave the bridge), and 40 seconds for a train to pass the 500 meter long tunnel (from the front of the train to the rear of the train to leave the tunnel). How many seconds does it take for the train to pass the other 384 meter long train with 18 meters per second?

Speed: (800-500) / (55-40) = 300 △ 15, = 20 (M / s); length: 20 × 40-500 = 300 (m); time: (300 + 384) / (20 + 18), = 684 △ 38, = 18 (s); answer: it takes 18 seconds for the train to pass head-on