Formal:
* Do zobaczenia w przyszłym tygodniu. (pronounced: do zobachenia v pshishłym ti'godniu) - This is the most direct and formal way to say it.
* Miłego tygodnia! (pronounced: mi'łego ti'godnia) - This translates to "Have a nice week!" and is a polite way to say goodbye.
Informal:
* Do zobaczenia! (pronounced: do zobachenia) - This is a simple and informal way to say "See you!" and is often used with friends and family.
* W przyszłym tygodniu! (pronounced: v pshishłym ti'godniu) - This translates to "Next week!" and is a more casual way to say "See you next week."
Even more informal:
* W przyszłym! (pronounced: v pshishłym) - This is a very informal and casual way to say "Next week!" and is only suitable for close friends.
The best choice will depend on the specific situation and your relationship with the person you are talking to.