A Train Question About Math...I think

What you do is you subtract the length of the tunnel by the length of the train. 

3km-1km=2km 

Now I know that the train traveled 2km In 30 seconds. Now we need to transfer it into minutes. To do that we need to multiply 30•2=60. So we need to know how many kilometers it travels every minute. 2•2=4. The train travels 4km every minute. To find out how many on it travels in one hour we multiply 60 by 4. The answer will become 240km/h. So the train travels 240 kilometers every hour.