SAT Strategy #3: Substitution
When you are stumped, you can try substituting reasonable numbers into the unknowns. Though it takes more time, this can at least allow you to eliminate a couple of choices so you can guess more effectively. No penalty for wrong answers
Substitute with simple numbers (like 1, -1 or 0) when possible, or any other numbers that are easy and provide useful information. Pay attention to what the allowable values are for the unknown. Make sure you know which numbers are included in the different number families (see Preliminaries).
Substitute the given choices. If there is an order to how the choices are listed, you might start with choice C, and work down or work up if you can determine whether the answer should be smaller or larger.