I've been looking up resources for learning to do math proofs. I come across resources that are advanced and covering techniques like 'prove by contradictions' etc. However, what I need is to first understand each and every arithmetic components in every single line of proof.
For example, sometimes I will struggle why certain terms are grouped together and why certain transformation is legit. Why pushing something (operators, e.g. summation, derivative signs etc.) inside the blanket works sometimes and fail for another. These kind of things can be find here and there in math textbooks, but the techniques are so dispersed and not organized!
So my question is, what are the resources best for someone who find it hard even to read proof line by line? I'm imagining there is something that is summative and group all techniques together for beginner to get a good grasp of all those essential/fundamental arithmetic operations needed for understanding every single line of proof.
Thanks in advance!