CCSS.Math.Content.HSA-REI.B.3

MathGrades 9–12Reasoning with Equations and Inequalities

The standard

Solve linear equations and inequalities in one variable, including equations with coefficients represented by letters.

Common Core State Standards for Mathematics

What this standard means

Students need to solve one-variable linear equations and inequalities, including cases with fractions, decimals, negatives, variables on both sides, and parameters like a, b, or k. They should show legal steps, keep equations balanced, and handle inequality signs correctly when multiplying or dividing by a negative.

Mastery looks like choosing efficient moves, explaining each step, and giving answers in forms like x = 7, x < 3, or x = (b - c)/a. Students often get stuck distributing negatives, combining unlike terms, clearing fractions, and treating letter coefficients as if they were extra variables to solve for.

Ways to teach it

  • Use algebra tiles or balance mats to model 3x + 2 = 11, then match each move to written equation steps.
  • Ask students to explain why dividing both sides of -2x < 10 changes the inequality sign, using words and one number check.
  • Give four problems on an exit ticket, one with variables on both sides, one inequality, one fraction, and one letter coefficient.
  • Use a cell phone plan equation C = 25 + 0.10m and ask students to solve for minutes given a budget.

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Related standards

Standard text verified against corestandards.org on July 10, 2026.

Page updated July 10, 2026.

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