Basic math.
Skip to parts that you need to refresh on.
Protip: 9 times out of 10 it will be the chapters covering algebra basics, and trig identities.
Proofs are covered but its not the emphasis of the book. In the introduction he states its meant as a refresher for people preparing for college math at Calc I, or for precalc in high school.
Here is more protip:
If you want to learn proofs, use book of proof.
Do not go to spivak for Calculus until you have completed an actual calculus course, or learned from Stewart calculus.
