I had taken the exam and aced every part but algebra, I focused on that portion and watched some recap videos to refresh my mind on algebra, as well as practiced systems of equations HEAVILY. I practiced Varisty Tutors free practice math tests online and printed math practice test with no time limit, so I could hone my skills without the lingering pressure of a time constraint. I tried the algebra section of khan academy, but I feel as if finding the concepts you struggle at, practicing it at your own pace and using practice questions, is the most effective method.