A railway bridge length is 180 meter and a train cross the bridge in 20 seconds but take time 8 sec to cross a men standing on bridge. Find spped and length  of the train.

Assume the length of train is x meters,

So train covers x meter in 8 sec and (x+180) in 20 sec.

(x/8) = ((x+180)/20)

20x = 8(x+180)

x = 120

length of train is 120 meter.

speed of train is = 120/8 m/sec

                      = 15 * 18/5 kmph

                      = 54 kmph

m/sec = m/sec = (15 *18/5) kmph = 54 km