**Vocabulary**

transform, two-step equation

**TEKS** 8(1)(B), 8(1)(C), 8(1)(D), 8(8)(C)

When you write an equation, you set two expressions equal to each other.

When you solve an equation, you find the value of the variable that makes the two expressions equal.

Sometimes, both expressions contain a variable term.

To solve this kind of equation, bring all of the variable terms to the same side of the equation.

**TEKS** 8(1)(C), 8(8)(C)

**Intro**

You can use algebra tiles to model equations with integer coefficients and variables on both sides of the equation.

**Example Using Models to Solve Equations With Variables on Both Sides**

What is the value of *x* when the expression 6*x* − 9 equals the expression 4*x* + 3?

**Solution**

Use algebra tiles to solve the equation 6*x* − 9 = 4*x* + 3. Begin by representing the two expressions.

Digits, Grade 8, Volume 1, Homework Helper
Unit A: Number and Operations
Math Symbols
Formulas Measures
Properties

Topic 1: Rational and Irrational Numbers

Unit B: Proportionality
- 1-1: Exploring Irrational Numbers
- 1-1: TEKS Practice
- 1-2: Approximating Irrational Numbers
- 1-2: TEKS Practice
- 1-3: Comparing and Ordering Rational and Irrational Numbers
- 1-3: TEKS Practice
- 1-4: Exploring Scientific Notation
- 1-4: TEKS Practice
- 1-5: Using Scientific Notation to Describe Very Large Quantities
- 1-5: TEKS Practice
- 1-6: Additional Problem Solving
- 1-6: TEKS Practice

Topic 2: Proportional Relationships, Lines, and Linear Equations
Topic 3: Defining and Comparing Functions

Unit C: Expressions, Equations, and Relationships
- 2-1: Representing Proportional Relationships
- 2-1: TEKS Practice
- 2-2: Linear Equations: y = mx
- 2-2: TEKS Practice
- 2-3: The Slope of a Line
- 2-3: TEKS Practice
- 2-4: Unit Rates and Slope
- 2-4: TEKS Practice
- 2-5: The y-intercept of a Line
- 2-5: TEKS Practice
- 2-6: Linear Equations: y = mx + b
- 2-6: TEKS Practice
- 2-7: Distinguishing Between Proportional and Non-Proportional Situations
- 2-7: TEKS Practice
- 2-8: Additional Problem Solving
- 2-8: TEKS Practice

Topic 4: Using the Pythagorean Theorem
Topic 5: Surface Area and Volume
Topic 6: Linear Equations in One Variable
Topic 7: Reasoning in Geometry
Topic 8: Simultaneous Linear Equations

English/Spanish Glossary
Formulas
- 7-1: Angles, Lines, and Transversals
- 7-1: TEKS Practice
- 7-2: Reasoning and Parallel Lines
- 7-2: TEKS Practice
- 7-3: Interior Angles of Triangles
- 7-3: TEKS Practice
- 7-4: Exterior Angles of Triangles
- 7-4: TEKS Practice
- 7-5: Angle–Angle Triangle Similarity
- 7-5: TEKS Practice
- 7-6: Additional Problem Solving
- 7-6: TEKS Practice

- 8-1: What are Simultaneous Linear Equations in Two Variables?
- 8-1: TEKS Practice
- 8-2: Estimating Solutions of Simultaneous Linear Equations by Inspection
- 8-2: TEKS Practice
- 8-3: Solving Simultaneous Linear Equations by Graphing
- 8-3: TEKS Practice
- 8-4: Solving Simultaneous Linear Equations Using Substitution
- 8-4: TEKS Practice
- 8-5: Additional Problem Solving
- 8-5: TEKS Practice