Exercise 1
Solve x + 9 = 14.
Show answer and check
x = 5
Why: Subtract 9 from both sides: x + 9 - 9 = 14 - 9, so x = 5.
Check: Substitute 5 into the original equation: 5 + 9 = 14, which is true.
Free original lessons
Teach solving linear equations with one or two inverse operations using a structured two-column workspace and clear step-by-step reasoning.
Solving an equation means finding the value of the variable that makes the statement true. For linear equations that need one or two inverse operations, the goal is to undo operations in reverse order while keeping the equation balanced. This lesson provides a consistent workspace: left column for the equation and each inverse operation, right column for the resulting simplified line. The convention is to show the operation applied to both sides on the same line, then simplify. Numerical examples are hypothetical and chosen for easy arithmetic; always measure your own equipment if printing or handwriting constraints matter.
Practice materials: Printable downloads are not available for this lesson yet. Use the instructions and four exercises below.
A one-step equation contains one operation acting on the variable, such as addition, subtraction, multiplication, or division. To isolate the variable, apply the inverse operation to both sides. For x + 7 = 15, subtract 7 from both sides to get x = 8. For 4x = 20, divide both sides by 4 to get x = 5. For x/3 = 6, multiply both sides by 3 to get x = 18.
Keep the workspace tidy: write the original equation, then on the next line write the inverse operation applied to both sides, then the simplified result. Check by substituting the value back into the original equation.
A two-step equation has two operations acting on the variable, such as 3x + 4 = 19. Undo operations in reverse order of standard arithmetic: first undo addition or subtraction, then undo multiplication or division. For 3x + 4 = 19, subtract 4 from both sides to get 3x = 15, then divide both sides by 3 to get x = 5.
For equations like x/2 - 5 = 1, first add 5 to both sides to get x/2 = 6, then multiply both sides by 2 to get x = 12. Always keep the equation balanced by performing the same operation on both sides.
Use a two-column workspace. Left column: write the equation, then each inverse operation on its own line, showing the operation applied to both sides. Right column: write the simplified result after each step. For example, left column: 2x + 3 = 11; subtract 3 from both sides; 2x = 8; divide both sides by 2. Right column: x = 4.
Handwriting varies: x-height is measured from baseline to midline, and letter styles differ. Accept any legible style that clearly distinguishes the variable from operators and numbers. The rubric below allows valid alternatives rather than a single universal answer.
Solve 5x - 7 = 18 using inverse operations and show each step.
Add 7 to both sides: 5x = 25. Divide both sides by 5: x = 5. Check: 5(5) - 7 = 25 - 7 = 18, which matches the right side.
Solve x + 9 = 14.
x = 5
Why: Subtract 9 from both sides: x + 9 - 9 = 14 - 9, so x = 5.
Check: Substitute 5 into the original equation: 5 + 9 = 14, which is true.
Solve 6x = 42.
x = 7
Why: Divide both sides by 6: 6x / 6 = 42 / 6, so x = 7.
Check: Substitute 7 into the original equation: 6(7) = 42, which is true.
Solve 2x + 5 = 17.
x = 6
Why: Subtract 5 from both sides: 2x = 12. Divide both sides by 2: x = 6.
Check: Substitute 6 into the original equation: 2(6) + 5 = 12 + 5 = 17, which is true.
Solve x/4 - 3 = 2.
x = 20
Why: Add 3 to both sides: x/4 = 5. Multiply both sides by 4: x = 20.
Check: Substitute 20 into the original equation: 20/4 - 3 = 5 - 3 = 2, which is true.
An inverse operation undoes another operation. Addition and subtraction are inverses; multiplication and division are inverses.
Standard arithmetic applies multiplication before addition. To isolate the variable, reverse that order: undo addition or subtraction first, then multiplication or division.
Substitute the value back into the original equation and simplify both sides. If they are equal, the solution is correct.
For two-step equations, undo addition or subtraction before multiplication or division. For one-step equations, apply the single inverse operation. Keep both sides balanced.