Explanation

To find the speed of the train, we can use the formula:

Speed = Distance / Time

In this case, the distance the train travels is the sum of the length of the train and the platform: 80 meters + 120 meters = 200 meters

So the speed of the train is: Speed = 200 meters / 20 seconds = 10 meters/second

Alternatively, we can convert the unit to km/h Speed = 10 x (3600/1000) = 36 km/h

So the train is traveling at a speed of 10 meters/second or 36 km/h.