What chapter does season 3 of Attack on Titan finish at?

Question

I want to start reading the manga for Attack on Titan since I can't wait 6 months for season 3.5.

What chapter should I start reading from?

Answer 1

Chapter 73 and it’s easier to find because some of the chapter names are similar to the episode names.

Answer 2

For the second part of Season 3 its Chapter 90