A train 200 m long takes 20 seconds to cross a man walking at 10 kmph in a direction opposite to that of  the train Find the speed of the train?

:  Distance = 200 m,  Time = 20 sec,      Speed of  man = 10 kmph

Relative speed of  train = $\frac{D}{T}=\frac{200}{20}=10m/\sec$

$=10\times \frac{18}{5}=36kmph$

$Speedoftrain=(36-10)=26kmph$