A train 250 m in length is travelling at a speed of 28 kmph .in how many seconds will it cross another 250 m long train coming in opposite direction at a speed of 22 kmph?

Let the first train take x sec to cross the othe train. 

Speed of the first train - 28km/h = 70/9 m/s

Speed of the second train = 22km/h = 55/9 m/s

 

The first train needs to cover 250m in order to pass the other train, but, since both the trains are travelling in the opposite direction

 

So, 250 = 70/9x + 55/9x

x = 18 sec