Two-Step with Decimals

Part of the Fundamentals section of Coddy's Math journey. Lesson 42 of 64.

1.2x + 0.4 = 2.8 is a two-step equation with decimals in every seat. Same order as always: subtract 0.4 from both sides, then divide by 1.2.

1.2x = 2.4

x = 2

Check: 1.2 × 2 + 0.4 = 2.8.

If the decimals bother you, multiply every term by 10 first (12x + 4 = 28) and solve with whole numbers; that is clearing a denominator of 10. Either way, the equation is the same two layers you have undone twenty times by now.

Challenge

Solve the equation 1.5x - 0.5 = 4 for x.

Try it yourself

1.5x - 0.5 = 4

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 Inside Negatives in Two Steps Recap: 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

2One-Step Equations

Undoing Addition Undoing Subtraction Undoing Multiplication Undoing Division Inverse Operations Recap: One-Step Equations

5Tidying First

Like Terms Terms and Numbers Mixed The Distributive Property Distributing a Subtraction Tidy, Then Solve Recap: Tidying First

8Decimals and Percent

Decimal CoefficientsTwo-Step with DecimalsAdding a Percent Percent Equations Recap: Decimals

11Formulas

Using a Formula Finding a Missing Value Solving for a Letter Temperature Recap: Formulas

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