Solving One-Step Equations (Grades 5–6)
An equation is a statement that two things are equal, with a letter standing in for an unknown number — like x + 5 = 12.
Understanding solving one-step equations
"Solving" it means finding the value of x that makes the statement true. The key idea: an equation is a balance, and to keep it balanced you must do the same thing to both sides. To get x alone, undo whatever is happening to it using the opposite operation — if 5 is added, subtract 5 from both sides.
Seeing it in action
Worked example
Solve x + 5 = 12.
5 is added to x, so subtract 5 from both sides: x + 5 − 5 = 12 − 5.
x = 7. (Check: 7 + 5 = 12 ✓.)
x + 5 = 12 balances when x is 7.
A common mistake, and the fix
Doing the same operation instead of the opposite one, or changing only one side.
In x + 5 = 12, adding 5 gives x + 10 = 17, which is no closer to x alone. Subtract 5 from both sides: x = 7. Check: 7 + 5 = 12.
Try a few
x − 4 = 9
add 4.
3x = 21
divide by 3.
x/2 = 6
multiply by 2.
Function Foundry
A calm pre-algebra game for function machines, inverse operations, and solving for an unknown.
Try it in Numeris.
A short lesson, then practice with feedback on every answer.
Put the reasoning on paper.
Try six fraction, angle, perimeter and area questions with explained answers, for grades 4–6.
Free printable · 3 pagesText version (screen-reader friendly): Draw it. Explain it. Math sample
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