<p>Back in high school, I didn’t use the textbook at all and got a 5 on both exams. The Barron’s prep book was very helpful, but if you still want to make a good investment, I’ve used Gregory Mankiw’s Principles of Economics.</p>
<p>You should spend as much time as you need until you understand the graphs, terms and concepts. Preparing for both exams is very efficient, as you kill two birds with one stone. </p>