I took the NLN Pax-RN exam last august and studied the PAX-RN reviewer by NLN. It gave me the basics in math. You need to study and practice a lot in Math since I found it the hard way. scored 30 out of 40 match questions and did OK but I had to guess on the last 10 questions since I run out of time.
For the science portion, I used the AP reviewers for Biology, Physics, and Chemistry. Make sure you borrow the text books for these subjects from the library to get more in depth explanation since these reviewers only give you the outline.
Hope this helps.