Questions & Answers about U torbi su ključ i kišobran.
Because after u meaning in for a fixed location, Serbian uses the locative case.
- base form: torba = bag
- locative singular: torbi = in the bag
So:
- u torbi = in the bag
If you used torba, that would just be the dictionary form, not the correct form after u in this sentence.
It is locative singular.
The noun torba is feminine, and its locative singular form is torbi.
This is a very common pattern:
- škola → u školi
- soba → u sobi
- torba → u torbi
So the sentence begins with a prepositional phrase in the locative: u torbi.