Skill: Solve one-step subtraction equations

Explanation and Free Practice Resources

Solving one-step subtraction equations involves determining the unknown in forms such as $x-a=b$ and $a-x=b$ , with integers, fractions, or decimals, by using the inverse relationship between subtraction and addition while preserving equality. Number-line and symbolic representations clarify subtraction direction and signed values, and substitution verifies the solution; multi-step equations and more advanced algebraic generalizations are outside this scope.

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Detailed Explanation: Solve one-step subtraction equations

A subtraction equation has the unknown with a number being subtracted, such as

x-a=b.

To isolate $x$ , use the inverse operation of subtraction: add the same number to both sides. This keeps the equation balanced.

Example

Solve:

x-4=9

Step 1: Add $4$ to both sides.

x-4+4=9+4

Step 2: Simplify.

The $-4$ and $+4$ cancel on the left:

x=13

So, the solution is

\boxed{x=13}.

Check the solution by substituting $13$ for $x$ in the original equation:

13-4=9

Since $9=9$ , the solution is correct. On a number line, starting at $13$ and moving $4$ units left lands on $9$ .

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Linear Equation - One Variable, Two Terms, Add and Subtract

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