91Ó°ÊÓ

When solving a linear equation, one of the first steps is to isolate the variable. This means getting the variable on one side of the equation by itself. In the exercise provided, you have the equation:
``` d - 3.9 = 8.2 ``` Make sure to clearly identify the terms you need to move. In this case, you need to get rid of the -3.9 attached to d. You do this by performing the opposite operation. Since -3.9 is subtracted, you should add 3.9 to both sides of the equation. Keep in mind that whatever you do to one side, you must do to the other to maintain balance.

By adding 3.9, you successfully isolate the variable d.

Once you've isolated the variable, the next step is to simplify both sides of the equation. Simplify means performing arithmetic operations necessary to reduce the expressions involved.

Let's continue from the example:
```
d - 3.9 + 3.9 = 8.2 + 3.9
```
On the left side, -3.9 + 3.9 cancel each other out, leaving d.
On the right side, you simplify the addition: 8.2 + 3.9 equals 12.1.
Now the simplified equation will look like this:

``` d = 12.1 ```
Simplifying is crucial because it allows you to reach the final answer in a clear and manageable way. It also makes it easy to check your work!

In prealgebra, equations like these are the foundation for understanding more complex math concepts. These problems help students learn how to manipulate numbers and variables.

Mastering these foundational skills is essential for success in algebra and beyond. With exercises like: ```
d - 3.9 = 8.2
```
you encounter basic arithmetic operations and learn to think logically about how to isolate variables and simplify equations. Solving such simple prealgebra equations involves basic operations, but the process is the same for more complicated problems later on:

• Isolate the variable
• Simplify both sides of the equation
• Ensure the equation remains balanced

Keep practicing! The more you work on these problems, the more confident you'll become with solving any kind of equation.