What this skill covers
SAT Algebra covers solving and interpreting linear equations and inequalities in one or two variables, and systems of two linear equations. A recurring question type asks what a specific number in an equation represents in context — usually a rate (slope) or a starting value (intercept).
For systems of equations, adding or subtracting the two equations to eliminate a variable is almost always faster than solving for one variable and substituting, especially under time pressure.
Worked examples
Example 1
A delivery fee is modeled by y = 3x + 6, where x is the number of packages and y is the total fee in dollars. What does 6 represent?
A. The fee per package
B. The number of packages delivered
C. The maximum possible fee
D. The fee charged even with zero packages
Why: In y = mx + b, the constant b is the value of y when x = 0 — the fixed base fee before any per-package charge.
Example 2
If the system x + y = 10 and 2x − y = 5 has solution (x, y), what is x?
A. 5
B. 3
C. 4
D. 6
Why: Adding the two equations eliminates y: 3x = 15, so x = 5 — always check whether adding or subtracting cancels a variable before solving either equation individually.
How to practice this on TSI Practice Prep
Open SAT Practice to answer original SAT questions on SAT Algebra, get an explanation for every choice, and see this skill tracked separately in your progress and mistake review.
Practice score estimates are learning indicators, not official scores or admission guarantees.