Introduction
In this lesson, you will learn how to solve for a variable on one side of an equation when fractions, addition, and subtraction are involved.
This video illustrates the lesson material below. Watching the video is optional.
- Solving for a Variable on One Side: Part 4 - Addition and Subtraction using Fractions (09:59 min) | Transcript
Solving for a Variable on One Side Using Addition, Subtraction, and Fractions
When solving for variables with fractions instead of whole numbers, add the additive inverse:
- Additive inverse: Number when added to another number equals zero.
Example 1
If you look at the number line, you have 2,
Example 2
You can think of this in another way by using your skills with adding and subtracting fractions. You know that you need to find a common denominator for both fractions if you want to perform any arithmetic. In this example, you will solve for
It’s important to note that the variable can be on either side of the equal sign. You follow the same rules for solving for the variable when x is on the right-hand side.
Example 3
You can check this answer by substituting
Things to Remember
- When dealing with a whole number, a fraction, or a decimal, add the additive inverse to both sides of the equation to isolate the variable.
- As a rule, you can remember additive inverses as having the opposite sign (positive or negative) as the number. This is true with fractions as well.
- Also remember, in order to add or subtract fractions, they must have a common denominator.
Practice Problems
Solve for the variable: (Solution (Solution (Solution (Solution (Video Solution (Solution (Video Solution