We transitioned the Math Prefresher booklet into a Rmarkdown (bookdown) document and into a public github repo in 2018, so typos, corrections, additional explanations, are especially welcome.
All changes should be made in the .Rmd files in the project root. Especially if the changes go beyond changing certain words, please verify that that the entire book compiles both in html and in pdf before submitting if you can get the XeLaTeX settings on your computer aligned so that building produces a PDF as well as a HTML page.
To contribute a change, please make a pull request.