If S has n pencils, R has n - 4, and T has twice as many as R, which expression represents R's pencils?

• A. n - 4
• B. n + 4
• C. 2n
• D. n/2

Answer: (A)

The idea is to translate the statement about R directly into an algebraic expression. Since R has n − 4 pencils, that expression already represents exactly how many pencils R has. The other details about S and T don’t change R’s amount—they just give context about how the others relate to R. If you tried any of the other forms, they’d imply relationships not stated (for example, R having four more than S, or R being twice S, or R being half of S), which isn’t what the problem describes. So the expression that represents R’s pencils is n − 4.