B. {−3, 4}

      C. {−2, 6}

      D. {12, 13}

      E. {13}

On standardized tests, reasoning questions will usually have variables (unknowns in the form of letters or symbols) in both the question AND answer. 

You may use the PION strategy for these problems. PION stands for Plug In Own Numbers. Define hypothetical values for the unknown variables. Write down the values you will be plugging in. Then plug the number into the scenario presented in the question and determine which answer choice results in the same value. 

Make sure to plug in every answer choice (especially for questions in the second half of the test… there may be “trick” answers so get into the habit of trying out every single answer choice instead of eliminating a choice because it looks wrong). If you’re unable to eliminate every answer choice with the number(s) you define/plugged in, select another set of numbers and plug in again. Do remember that any instance of an answer choice NOT working based on numbers you chose that fit the criteria of the problem means that choice is definitely wrong. 

Example: If N is a positive odd integer, which of the following is even:

      I. N + 2

      II. 3N + 1

      III. 3 (N+1)

A. I

B. II

C. III

D. II and III

Solution: Select a value for N that fits the criteria of the question. Write down N=3. Then plug in 3 for N to I, II, and III, writing down the value of each next to it. I = 5, II = 10, and III = 12. Since 10 and 12 are both even, select choice (D).

Note: In some cases, the value you chose for the variable may work for more than one answer choice. If this happens, select another number for the variable, and then plug it in again to the un-eliminated answer choices.

With that in mind, I suggest that you skip immediately to the questions. Do not waste time reading the passages. Do the questions in order with the following approach: identify where to go looking for the answers and then what to look for.