Most universities or colleges have an alert system through the Office of Student Services to notify those students in jeopardy; I am speaking from experience and look at me now, I passed the NCLEX at 75 the first time--YOU WILL DO IT TOO! have faith in yourself. In the meantime, ask to speak with your instructor and go over the math together, utilize your schools
tutoring center if they have one or ask to be paired with a mentor until you feel comfortable with your study habits. Speaking of study habits, take good notes, then condense, color highlight with multi colors, use flash cards, skim texts, use online support, and tape record lectures if allowed. If you have test anxiety or have a learning disability undiagnosed at the time (again I speak from experience) and it is chronic, you may have recourse through the Office of Student Disabilities for test-time accommodation or a quiet environment.
But first things first my friend, make an appointment with your instructor immediately so you have time to make any necessary adjustments. Good luck.