Hi everyone, I am an aspiring research scientist in deep learning, I already have some engineering experience with models, but I wanted to learn formal mathematics for research, I'm in high school and I'm reading Linear Algebra Done Right by Sheldon Axler (after dopping analysis 1 by terence tao) and although I was able to solve almost all the problems in the first chapter, the book became extremely cryptic and ambiguous by page 30. I'm also annoyed by the use of Calculus topics as examples (I know Calculus, but not very formally, that's why I wanted to do real analysis). I'm not blaming Axler, on the contrary, the problem is clearly my lack of mathematical maturity, so I wanted to ask you: which books do you consider the most formative in this sense? I mean, besides those boring books like How to Prove It or Book of Proof (nothing against them, but they're too boring, it's just me), in this sense I've heard good opinions about Spivak's Calculus, is it really that good? How much transfer learning is there in mathematics? Will learning to do proofs in one area of ​​mathematics make me better at doing them in another area?