I’m in this boat as well. I dropped out of first year university some years ago and have subsequently forgot all the higher level math that I spent years learni

I’m in this boat as well. I dropped out of first year university some years ago and have subsequently forgot all the higher level math that I spent years learning. I can’t even understand the notation which used to be so familiar. From my experience you have to start from scratch since some concepts are foundational and will block progress later if you don’t know them. I have started with Khan Academy just answering questions on my phone. It’s a grind but I do it later in the day when my cognition is reduced. I imagine later on I will have to get a tutor.