How do I know which operation to undo?

Look at what is directly attached to the variable. "x + 5" shows addition, so subtract. "5x" shows multiplication, so divide. "\frac{x}{5}" shows division, so multiply. Only one operation is present in a one-step equation.

Why do I have to do the same thing to both sides?

An equation says two things are equal — a balanced scale. Changing one side only would break the equality, and the "solution" you get would no longer satisfy the original equation.

Do I always have to check my answer?

It takes five seconds and catches nearly every slip: substitute your answer back into the original equation and confirm both sides match. Photo Math Solver shows this check as its final step too.

What if the answer is a fraction or a negative number?

That is completely normal. 4x = 6 gives x = \frac{3}{2}, and x + 9 = 2 gives x = -7 — an answer does not need to be a positive whole number to be right.

What grade level are one-step equations?

Typically grade 6–7 (pre-algebra). They are the foundation for two-step equations, multi-step linear equations, and everything after, so fluency here pays off for years.

Is Photo Math Solver free to use?

You can start solving equations for free by adding the Chrome extension — try it on your own worksheet before deciding if you need anything more.

AI-Powered Pre Algebra Solver

Solve One-Step Equations Step by Step

Screenshot any one-step equation from your worksheet and see exactly which inverse operation solves it — in seconds.

Try for free

4.4/5 from 35 Chrome Web Store reviews · 2,000+ users

Works on any screenshot — textbook, PDF, or worksheet
Full step-by-step solutions, not just the final answer
Free to start — no account needed

school-portal.com/homework-worksheet.pdf

Photo Math Solver Solved

x + 9 = 16

1The variable has $9$ added to it, so subtract $9$ from both sides: $x + 9 - 9 = 16 - 9$ .
2Simplify: $x = 7$ .
3Check: $7 + 9 = 16$ ✓.

On this page01Definition 02Formulas 03Methods 04Examples 05Practice 06Mistakes 07FAQ

01Definition

What is a one-step equation?

A one-step equation is an equation you can solve by undoing exactly one operation. In $x + 9 = 16$ , the only thing happening to $x$ is "add 9" — so one opposite move, subtracting 9 from both sides, reveals the answer.

The big idea is balance: an equation is a scale, and whatever you do to one side you must do to the other. Every equation type you will ever meet — two-step, linear, quadratic — is built on this single move done repeatedly.

There are only four cases, one per operation: something added to $x$ , subtracted from it, multiplying it, or dividing it. Each is undone by its inverse (opposite) operation.

Where you'll actually use this

Sharing costs: "the three of us split the bill evenly and each paid $14 — what was the total?" is $\frac{x}{3} = 14$ .
Shopping: "after a $5 coupon I paid $23" is $x - 5 = 23$ .
Cooking: scaling a recipe that serves 4 up to 12 servings means solving $4x = 12$ .
Saving: "I need $60 and already have $42" is $42 + x = 60$ .

02Formulas

The formulas you need

Keep these on hand — every method below builds on them.

Undo addition

x + a = b \;\Rightarrow\; x = b - a

Subtract the added number from both sides.

Undo subtraction

x - a = b \;\Rightarrow\; x = b + a

Add the subtracted number back to both sides.

Undo multiplication

ax = b \;\Rightarrow\; x = \frac{b}{a}

Divide both sides by the coefficient in front of x.

Undo division

\frac{x}{a} = b \;\Rightarrow\; x = ab

Multiply both sides by the divisor.

03Methods

How to solve one-step equations

Pick the method that fits the problem in front of you.

When to use it: When a number is added to or subtracted from the variable:

x + 5 = 12

x - 7 = 12

1Identify what is attached to $x$ : " $+\,5$ " means addition is happening.
2Apply the opposite operation to both sides: subtract $5$ from each side.
3Simplify both sides — the left side collapses to just $x$ .
4Check by substituting the answer back into the original equation.

04Worked examples

One-Step Equations, solved step by step

From easy to hard — pick a problem to see its full solution.

x + 9 = 16

1The variable has $9$ added to it, so subtract $9$ from both sides: $x + 9 - 9 = 16 - 9$ .
2Simplify: $x = 7$ .
3Check: $7 + 9 = 16$ ✓.

Try it on your own one-step equations homework

Photo Math Solver reads a one-step equation straight from a screenshot — a worksheet, a textbook page, an online quiz — and shows the single inverse operation that solves it, applied to both sides, with the check at the end. No retyping, and no wondering whether to add or subtract.

05Practice

Now you try

Work each one on paper first, then check your answer.

Problem 1

x + 11 = 20

Problem 2

x - 6 = 14

Problem 3

8x = 56

Problem 4

\frac{x}{3} = 7

Stuck on your one-step equations homework? Screenshot it

If a one-step equation on your worksheet has awkward numbers or fractions, screenshot it with Photo Math Solver instead of retyping it — it reads the equation straight off the page and shows the same isolate-the-variable steps you would do by hand.

06Common mistakes

Where points get lost

Each of these shows up on real graded work — and each has a simple fix.

The mistake	Why it happens	The fix
Applying the inverse operation to only one side.	The focus is on "getting $x$ alone," so the other side of the scale gets forgotten.	Write the operation under both sides before simplifying anything — the equation is a balance, and both pans must change together.
Using the same operation instead of the inverse — adding when you should subtract.	Seeing " $+\,7$ " primes your brain for addition, so you add 7 again instead of undoing it.	Say the undo out loud: "seven is added, so I subtract seven." Opposite pairs: $+\leftrightarrow-$ and $\times\leftrightarrow\div$ .
Treating $5x$ as " $x$ plus 5" and subtracting.	A number sitting next to a letter does not show its multiplication sign, so the operation is easy to misread.	$5x$ always means $5 \cdot x$ — undo it by dividing. Subtraction only applies when you see an explicit $+$ or $-$ .
Dropping the sign when the coefficient is negative.	Dividing $-3x = 12$ by $3$ instead of $-3$ feels close enough, but gives $x = 4$ instead of $x = -4$ .	Divide by the entire coefficient including its sign, then check by substituting: $-3(-4) = 12$ ✓.

Photo Math Solver shows every intermediate step, so slips like these are easy to catch before they cost you marks.

07FAQ