I distinctly recall single-variable algebra in elementary school here in Poland. It may vary from country to country.
Edit: also, where might I find some old Polish example exams and marking schemes? ChatGPT is inherently multilingual, so I might as well.
This thread is no longer on my first page of comments, so I may forget to reply, but I've downloaded those and do intend to test it against those exams, and will put the write up here: https://github.com/BenWheatley/Studies-of-AI