I've been working on addressing this problem through my books (links in profile), because I think it's important to consider the general audience, which means including all the "high school math prerequisites in each book.
For anyone who is wondering how to fill in these basics skills, the khan academy videos + interactive exercises are probably the best way to go: https://www.khanacademy.org/ If you prefer a book on the topic, check mine: https://nobsmath.com Here is the concept map from the book that lists the various topics normally covered in high school math that I think everyone should know: https://minireference.com/static/conceptmaps/math_concepts.p...
See also similar concept maps from the other books: https://minireference.com/static/conceptmaps/math_and_physic... and https://minireference.com/static/conceptmaps/linear_algebra_...