For the past 17 years I have worked in the adult education department of our local community college. My students choose from the HSE or HiSet exam. I teach all four subjects needed to pass those exams. Four years of high school knowledge seems like an overwhelming amount to tackle. But unlike exams you may have taken in the past, the tests don't want memorization of times and places but the use of evidence to answer questions and draw conclusions. The math is around 55% algebra so that might need some review, but it is mostly Algebra 1 and, I promise, is manageable. You can do this. Hopefully, I can help.