The placement tests are extremely easy. There’s really no need to worry or study at all. The math placement test was basically a bit of pre-calculus and adv algebra, and mojority of the questions you could solve with basic algebra skills.
The chem placement test was so easy that you could simply use elimination/deduction skills to answer the questions. If your SAT score was high enough to be accepted into Davis this year, then I’m sure you would be capable of testing into MAT21A/CHEM 2A since you only really need about 50% on the test l0l.