We use prepositions to show how far things are:
Birmingham is 250 kilometres from London.
Birmingham is 250 kilometres away from London.
It is 250 kilometres from Birmingham to London.
Sometimes we use an adverbial of distance at the end of a clause:
We were in London. Birmingham was 250 kilometres away.
Birmingham was 250 kilometres off.
London and Birmingham are 250 kilometres apart.
- Adverbials of distance 1
- Adverbials of distance 2