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.

Because oba bilety is the subject of the sentence, and in this kind of structure the noun stays in the nominative plural.

So:

• oba bilety są... = correct

Biletów is the genitive plural, which appears in other patterns, for example:

• pięć biletów = five tickets
• nie ma biletów = there are no tickets

This is a very common thing learners notice: after some numbers Polish uses nominative plural, and after others it uses genitive plural.

Because the subject is plural:

• bilet = singular
• bilety = plural

So the verb must also be plural:

• jest = is
• są = are

Since the sentence is about both tickets, the correct verb is są.

In a normal, complete sentence like this, no—you would normally keep it.

• Oba bilety są w torbie. = normal standard sentence

If you say:

• Oba bilety w torbie

that can sound like a note, a label, or very informal shorthand, but not the neutral full sentence an English speaker would usually want to learn first.

Because after w meaning in, Polish uses the locative case for location.

The dictionary form is:

• torba = bag

But after w in this sentence, it changes to:

• w torbie = in the bag / in a bag

So torbie is just the locative form of torba.

Polish does not use articles like a/an and the.

So torba / torbie can mean:

• a bag
• the bag

The exact meaning comes from context.

That means w torbie could mean either in a bag or in the bag, depending on the situation. English has to choose an article, but Polish usually does not.

No. Polish word order is more flexible than English word order because case endings do a lot of the grammatical work.

The sentence:

• Oba bilety są w torbie.

is a neutral, natural order.

But you can also say:

• W torbie są oba bilety.

That is also correct, but it puts more focus on where the tickets are.

So the words can move around more than in English, although some orders sound more natural than others.

Yes. That is also correct.

• oba bilety
• obydwa bilety

Both mean both tickets.

In practice:

• oba is shorter and very common
• obydwa is also common and can sound slightly more explicit or emphatic

The meaning is basically the same in this sentence.