It takes 24 seconds for a train to pass through the first tunnel of 500 meters, and then it takes 16 seconds to pass through the second tunnel of 216 meters?

It takes 24 seconds for a train to pass through the first tunnel of 500 meters, and then it takes 16 seconds to pass through the second tunnel of 216 meters?

Train speed (500-216) / (24-16) = 35.5 M / S
The distance is 35.5 × 24 = 852m
Train length 852 - 500 = 352m

It takes 45 seconds for a bus to cross the 860 meter long bridge and 35 seconds for a bus to cross the 620 meter long tunnel at the same speed

Suppose the speed X and the body length y of the bus
860+y=45x
620+y=35x
x=24
y=220

It takes 45 seconds for a bus to cross the 860 meter long bridge and 35 seconds to cross the 620 meter long tunnel at the same speed

The speed of crossing the bridge is (860 + L) / 45
Speed through tunnel: (620 + L) / 35
The two velocities are the same, so there is an equation:
　　(860+L)/45=(620+L)/35
Both sides multiply by 45 * 35 at the same time
　　35(860+L)=45(620+L)
　　30100+35L＝27900+45L
　　10L＝2200
L = 220 (m)
A: the length of this bus is 220 meters