According to your answers, it looks like you have a solid foundation in math, however, you missed this one problem. Factoring a quadratic is tough, but with the tricks taught in volume 5, it will be a snap. If everything has been easy up to this point, then you can start with volume 5 of the Learn Math Fast System.
RESULTS: The 9th Grade Level, however, the Learn Math Fast System is for all ages. Volume 5 covers 9th - 10th grade algebra, but there is no mention of grade level within the books.