What should you say in this situation?

Please take a look at this picture: https://imgur.com/a/tmJwjPB

The girl in this picture is sitting in a classroom. She has her shirt folded in on itself, which is why her back is visible, but she does not realize this. She also has her underwear sticking out of her pants. If you're a friend of hers and you're sitting right next to her, then should you tell her to pull her shirt down? Also, should you say anything about her underwear?