TEAS books are available for free in every public library. Get one, copy chapters and go one by one, till you understand the material.
Seeking help in community college is also not a bad idea, although it may or may not be free.
You can take your time, but, ultimately, you'll need this knowledge if you want to become a nurse. Good news, though, that pretty much everyone's brains can be developed if pushed hard enough and long enough. Mental acuity, thinking skills and concentration can be greatly improved at practically any age.There are things which are proven to add to it, doesn't matter what age they are started, if done consistently every day for months: aerobic exercise, stress management by yoga and meditation/prayer, getting enough of natural sleep, getting social by natural means (Facebook doesn't count), learning foreign languages, playing games which require creativity and analytics (chess, checkers), listening of classic music and reading.
Eight Habits that Improve Cognitive Function | Psychology Today