# Chapter 3: Linear Equations

**Basic**Created by: CK-12

Aside from simplifying algebraic expressions and graphing functions, solving equations is one of the most important concepts in mathematics. To successfully manipulate an equation, you must understand and be able to apply the rules of mathematics.

Mathematical equations are used in many different career fields. Medical researchers use equations to determine the length of time it takes for a drug to circulate throughout the body, botanists use equations to determine the amount of time it takes a Sequoia tree to reach a particular height, and environmental scientists can use equations to approximate the number of years it will take to repopulate the bison species.

In this chapter, you will learn how to manipulate linear equations to solve for a particular variable. You already have some experience solving equations. This chapter is designed to help formalize the mental math you use to answer questions in daily life.

- 3.1.
## One-Step Equations

- 3.2.
## Two-Step Equations

- 3.3.
## Multi-Step Equations

- 3.4.
## Equations with Variables on Both Sides

- 3.5.
## Ratios and Proportions

- 3.6.
## Scale and Indirect Measurement

- 3.7.
## Percent Problems

- 3.8.
## Problem-Solving Strategies: Use a Formula

- 3.9.
## Chapter 3 Review

- 3.10.
## Chapter 3 Test