I started reading Spivak's Calculus about a month ago and I'm at the end of chapter two, so this is not really calculus yet. However, I find the problems really difficult and the answer keys are not very helpful. I can answer some problems but a lot of them, I've no idea what I should even start with. Also, it takes me a very long time to do each problem. (10-15 minutes on average).
I've no prior experience to writing proofs, but I've watched a few youtube videos on it. The problem is generally not the proofs problems but the one where they say "Find a formula" or "derive this equation". Those, i can never do.
Is there some prior knowledge that I should know before reading this besides knowing how to do proofs? Or, are these problems generally difficult to begin with? Or, am I not paying attention to what's written in the chapter?
Also, should I look at/try every single problem are is doing like the first page of them sufficient? I had plan to do every problem in the first chapter but called it quits after they started putting epsilons everywhere.