# 7.4: Simplify Sums or Differences of Single Variable Expressions

**At Grade**Created by: CK-12

### Let’s Think About It

**License**: CC BY-NC 3.0

Marc is heading to his local ice cream store. This particular store doesn't have a lot of flavor choices, but they have the BEST vanilla ice cream around. Marc has taken orders from several of his neighbors, too, and has written them all down so that he can keep track of who wants what.

The Johnsons - two vanilla ice cream cones

The Mumfords - three vanilla ice cream cones

Jill Stales - one vanilla ice cream cone

The Porters - three vanilla ice cream cones

How can Marc write this information as an algebraic expression and then simplify it?

In this concept, you will learn how to simplify single variable expressions.

### Guidance

If an expression has only numbers, you can calculate its numerical value. However, if an expression includes variables, it is helpful to simplify the expression.

Look at this example.

Simplify the expression

When adding expressions with variables, it is important to remember that only like terms can be combined. For example,

Here is another example.

Simplify

*not* like terms because only one term includes the variable

Here is another example.

Simplify

Since

The answer is

Here is an example using decimals.

Simplify

Since

The answer is

### Guided Practice

Simplify the expression.

To simplify this expression, follow the order of operations and combine like terms in order from left to right. Here is what the expression looks like after the first two terms have been combined.

Next, perform the subtraction to get:

Finally, add the terms.

The answer is

### Examples

Simplify each sum or difference when possible.

#### Example 1

These are like terms, so add the numerical parts together.

The answer is

#### Example 2

These are like terms, so subtract the numerical parts.

The answer is

#### Example 3

These are not like terms.

The terms are not alike so you cannot combine them. The expression is in the simplest form already.

The answer is

### Follow Up

**License**: CC BY-NC 3.0

Remember Marc and all his vanillas?

Marc needs to write an expression to simplify his order: two vanillas, three vanillas, one vanilla, and three vanillas.

Let

Looking at this expression, you will see that the variables are all the same. Therefore, simply add the numerical part of each term.

The answer is

### Video Review

https://www.youtube.com/watch?v=C72lpuGQYo4

### Explore More

Simplify each sum or difference by combining like terms.

6a+7a 7x−2x 6y+12y 8a+12a 12y−7y 8a+15a 13b−9b 22x+19x 45y−12y 16a+18a+9a 14x−6x+2x 21a+14a−15a 33b+13b+8b 45x+67x−29x 92y+6y−54y

### Answers for Explore More Problems

To view the Explore More answers, open this PDF file and look for section 7.4.

### Image Attributions

**[1]****^**License: CC BY-NC 3.0**[2]****^**License: CC BY-NC 3.0

## Description

## Learning Objectives

In this concept, you will learn how to simplify single variable expressions.

## Related Materials

## Difficulty Level:

At Grade## Subjects:

## Search Keywords:

## Grades:

## Date Created:

Dec 02, 2015## Last Modified:

Dec 02, 2015## Vocabulary

**Save or share your relevant files like activites, homework and worksheet.**

To add resources, you must be the owner of the Modality. Click Customize to make your own copy.