Learn two-step equations
A two-step equation requires two inverse operations. Undo addition or subtraction first, then undo multiplication or division.
You will undo two operations in the right order and check the solution.
The idea in plain English
A two-step equation has two operations wrapped around the variable. Remove the outside operation first, like taking off a coat before a shirt.
After each move, both sides must still have the same value.
How to recognise this kind of question
- The variable is multiplied or divided and also has a number added or subtracted.
- The equation usually looks like ax + b = c.
- It takes two opposite operations to leave the variable alone.
Quick decision: Undo addition or subtraction first. Then undo multiplication or division.
The method
- Remove the added or subtracted constant from both sides.
- Divide or multiply both sides to isolate the variable.
- Check the result in the original equation.
Worked examples
3x + 5 = 26
- Subtract 5: 3x = 21.
- Divide by 3: x = 7.
Answer: x = 7
−2x + 7 = 19
- Subtract 7 from both sides: −2x = 12.
- Divide both sides by −2: x = −6.
- Check: −2(−6) + 7 = 19.
Answer: x = −6
Your turn—with help
4x − 3 = 25
Need a hint?
Remove the −3 before dividing by 4.
4x − 3 + 3 = 25 + 3
Show the answer and steps
- Add 3 to both sides: 4x = 28.
- Divide both sides by 4: x = 7.
- Check: 4(7) − 3 = 25.
Answer: x = 7
Watch out for this mistake
Incorrect: 3x + 5 = 26, so x = 26 ÷ 3 − 5
Why it fails: Dividing first also divides the +5 term, so this expression does not preserve the equation.
Do this instead: Subtract 5 first, then divide by 3.
Quick check
Try these without looking. Then open each answer to check your thinking.
2x + 5 = 17
Need a hint?
Subtract 5 first.
Show the answer and steps
- 2x = 12.
- x = 6.
Answer: x = 6
3x − 8 = 10
Need a hint?
Add 8 first.
Show the answer and steps
- 3x = 18.
- x = 6.
Answer: x = 6
−5x + 4 = 24
Need a hint?
Subtract 4, then divide by −5.
Show the answer and steps
- −5x = 20.
- x = −4.
Answer: x = −4
Common mistakes
- Dividing before removing the constant.
- Forgetting to perform an operation on both sides.
- Losing a negative sign during division.
Practice tips
- Write one balanced transformation per line.
- Use one-step equations as a warm-up.