Some time ago I used to go running.

[tufguy]

Some time ago I used to go running. I used to run on a road which was 3.5 kilometers long from one end to another. When I ran both sides (from starting point to end point and again from end point to starting point) it made a total of 7 kilometers.

Sorry for posting the question as it is.

I used to run there and back along a 3.5-kilometre road. Sorry I don't understand this "there and back". What does "there" mean here?

 

[emsr2d2]

It means "in one direction and then in the other direction".

You could have just Googled "definition of there and back". You'd have found this.