Questions & Answers about Oba bilety są w torbie.
Oba means both.
So oba bilety is not just two tickets in a general sense; it means both tickets, usually the two specific ones that matter in the context.
Compare:
- dwa bilety = two tickets
- oba bilety = both tickets
In many situations, both are possible, but oba sounds more like you are talking about a known pair.
Because the form of both changes depending on the type of noun it goes with.
Here are the main forms:
- obaj = with masculine personal nouns, especially groups of men, e.g. obaj studenci
- obie = with feminine nouns, e.g. obie torby
- oba = with masculine non-personal nouns and neuter nouns, e.g. oba bilety, oba okna
Bilet is a masculine inanimate noun, so oba is the correct form.