Home
Ctrl+k

Skill: Solve one-step addition equations

Explanation and Free Practice Resources

An addition equation represents an equality in which an unknown is combined with a known number, typically in forms such as x+a=bx+a=b or a+x=ba+x=b, with integers, fractions, or terminating decimals. Solving means preserving equality by using subtraction, the inverse of addition, to isolate the unknown and verifying the result by substitution; this reasoning applies to positive and negative quantities and does not include multi-step equations, variables on both sides, or nonlinear forms.

On this page:

Detailed Explanation: Solve one-step addition equations

An addition equation has an unknown added to a known number. To isolate the unknown, use subtraction, the inverse operation of addition. Whatever you do to one side, do to the other side to keep the equation balanced.

Solve:

x+7=−2x+7=-2

Step 1: Subtract 77 from both sides.

x+7−7=−2−7x+7-7=-2-7

Step 2: Simplify.

The (7−7)(7-7) cancels on the left:

x=−9x=-9

Step 3: Check your answer.

Substitute (−9)(-9) for xx in the original equation:

−9+7=−2-9+7=-2

Since the statement is true, the solution is

x=−9\boxed{x=-9}

Learn by doing: Solve one-step addition equations

Click a topic below to practice the foundational skills you'll need, learn the steps, or master this skill

    Your results

    Practice with unlimited practice problems

    One-Step Equation - Addition - Solve

      ?

      Download/Modify Free Grade 8 'Solve one-step addition equations' Worksheet

      Print this free 'Solve one-step addition equations' worksheet to practice this skill away from the computer. Click 'Modify' to easily customize this worksheet to your exact needs.

      Units Teaching This Skill

      These adaptive units introduce, teach, or reinforce this skill (Solve one-step addition equations) through scaffolded problems that grow in difficulty as concepts are understood.

        Explore More Grade 8 Math