I'm a re-igniting my passion for maths and recovering from math anxiety. I'm using Serge Lang's Basic Mathematics to re-learn useful high school topics before attempting more difficult subjects. I'm new to proofs as most of what I did before was computational.
The first few exercises ask me to justify each step using commutativity and associative to in proving the following identities:
I could use an example of how to go about this. Thank you.