Quick answer

A two-step equation can often be solved by undoing addition or subtraction first, then multiplication or division.

Identify the variable term

In 3x + 5 = 20, the variable is x and the term 3x means 3 multiplied by x.

Undo operations in reverse

Subtract 5 from both sides: 3x = 15. Divide both sides by 3: x = 5.

Check by substitution

Put 5 back into the original equation: 3(5) + 5 = 20. Both sides match.

Worked examples

  • 2x + 4 = 14 → x = 5
  • 5x - 3 = 12 → x = 3
  • x/4 + 2 = 5 → x = 12

Common mistake to avoid

Always do the same operation to both sides. Do not move a term across the equals sign without explaining the inverse operation.

Practice questions

Try these without looking at the answers first. Explain your reasoning aloud or write each step.

  • Question: 2x + 3 = 11 — Answer: x = 4
  • Question: 4x - 1 = 15 — Answer: x = 4
  • Question: x/3 + 1 = 5 — Answer: x = 12

What to learn next

Review the related lessons linked below, then practice independently. If you make an error, write down which rule you used and why it did not apply.

Explore FitGitt practice.