In a recent post, we took a look at a classic SAT algebraic word problem and explained how to solve it with an algebraic equation—the approach that all of your math teachers encouraged in class. But on the SAT, working a problem out algebraically isn't always the best strategy. Maybe the equation presents some concept that you’re not comfortable with. Or maybe your mind is just blanking. When you find yourself in this situation, it's time to try plugging in.

If you've spent even a little bit of time prepping for The Test, you're probably familiar with the “plug in” approach. Basically, you take the given answers and stick them into the problem to see which one works. But with a little method, you can use plugging in to shave some time off your test. The key is to always start with C. Let’s work through an example: