# Intro to Solving for Variables

By Emma Davis

Edited by Sophia Layton

Say you’re given an equation in the form ax + b = c. How would you go about solving this for x?

Think of it like you are undoing all the operations in the equation.

Let’s use **3x + 5 = 20** as an example. To solve for x, you want to have x alone on the left side of the equation. So the first step is to **undo the addition or subtraction**, which in this case, would be the **+ 5**.

__To undo addition, subtract__ the number being added from both sides of the equation.

__To undo subtraction,__the number being subtracted to both sides.

*add*## 3x + 5 = 20

- 5 - 5

## 3x = 15

You should be left with **3x = 15**. Now, the next step is to undo any multiplication or division. For this equation, we need to get rid of the 3 that is multiplying the x.

__To undo multiplication, divide__ each side by the coefficient (the number next to the variable- the one that is multiplying it. In this case, the coefficient is 3).

__To undo division,__each side by the divisor.

*multiply*## 3x = 15

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## 3

## x = 5

You should be left with x = 5. Congrats! You’ve solved it for x. To check your answer, insert the x value (what x ends up equal to) in place of x in the original equation. If the equation is true, you are correct!

## 3(5) + 5 = 20

## 15 + 5 = 20

## 20 = 20

Here are some more examples for reference!