Negatives in Two Steps

Part of the Fundamentals section of Coddy's Math journey. Lesson 21 of 64.

5 - 2x = 11 looks different because the unknown comes second, but the layers are the same: x is multiplied by -2 and then 5 is added. Subtract 5 from both sides, then divide by -2:

-2x = 6

x = -3

Check: 5 - 2 × (-3) = 5 + 6 = 11. True.

Read 5 - 2x as 5 + (-2x): the coefficient of x is -2, sign and all. Divide by -2, not by 2, and the answer comes out with the right sign on its own.

Challenge

Solve the equation 7 - 3x = 22 for x.

Try it yourself

7 - 3x = 22

Solve for x

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Fundamentals

1What an Equation Is

The Equation Finding the Unknown The Same to Both Sides Solved Means Alone Recap: First Equations

4Two-Step Equations

Two Layers to Undo Subtract, Then Divide Add, Then Divide A Division InsideNegatives in Two StepsRecap: Two-Step Equations

7Fractions in Equations

A Fraction Coefficient Clearing One Denominator Two Denominators A Fraction Around a Sum Cross-Multiplying Recap: Fractions

10From Words to Equations

Phrases into Expressions Sentences into Equations Consecutive Numbers Age and Money A Perimeter Problem Recap: Words

3Negative Numbers

Below Zero A Negative Answer Negative Coefficients The Opposite of x Recap: Negatives

6Variables on Both Sides

x on Both Sides Gathering the x's Numbers and x's Everywhere Parentheses on One Side When x Is Negative Recap: Both Sides

9Special Cases

No Solution Always True Checking a Solution Recap: Special Cases

12Final Challenges

Parentheses on Both Sides Fractions and x's Decimals on Both Sides The Story Problem