I am a career changer, too, and hadn't done high school math in 25 years. The GRE prep products still assumed more math than I was able to do. I don't even remember if I ever learned how to graph the slope of a line! I found the basic algebra, geometry, and statistics free online classes from Khan Academy to be extremely helpful as a first step. I had to go through those Khan classes before the Magoosh practice could then be helpful. (https://www.khanacademy.org) Good luck!