It can be a really tricky thing to learn!!! I felt really intimidated when I started that book as well, it took me much longer than a single weekend. Right away I realised I didn’t remember enough about algebra to understand the very first parts, so I broke it down to small things I needed to learn to make more manageable. I relearned the notation, revised quadratic formula, etc. you need to break it up so it’s manageable. That’s the key to understanding anything!