What is /sci/'s recommend website for free textbooks and lessons? I don't mind using open-source textbooks.
I'm looking to review math along with learning shit about marketing, business, econ, and finance, so I would like any recommendations for those as well.

I don't want to keep going through the college humiliation ritual just to end up unemployable (compsci major lol) but I want to learn what it takes to start and run my own business or get livable money off of investments, and I don't trust "influencers" to teach me.