Skill: Solve one-step addition equations

Explanation and Free Practice Resources

An addition equation represents an equality between two quantities, with an unknown whole-number addend or sum that can occur in either addend position, such as $n+275=600$ , $275+n=600$ , or $n+275=600$ . The learner reasons that subtraction finds an unknown addend, using the inverse relationship between addition and subtraction and checking that both sides remain equal; representations such as number lines and bar models clarify this relationship. The scope excludes negative numbers, fractions, decimals, and multi-step or highly generalized equations.

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Detailed Explanation: Solve one-step addition equations

An addition equation shows that two amounts are equal. To find an unknown addend, use subtraction because subtraction undoes addition.

Example:

n+275=600

Here, $n$ is the unknown number. We know the whole is $600$ , and one part is $275$ . Subtract the known part from the whole:

600-275=n

Now calculate:

600-275=325

So,

n=325

Check your answer by replacing $n$ with $325$ :

325+275=600

The equation is true, so the answer is correct. The unknown number is $\boxed{325}$ .

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One-Step Equation - Addition - Solve

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