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Solving Two-Step Linear Equations with Decimals

A two-step equation has two different operations. To solve a two-step equation, use inverse operations to undo each operation in reverse order.

Example :

Solve 4 y + 3.5 = 12.5 . Check the solution.

Undo addition. Subtract 3.5 from each side.

4 y + 3.5 − 3.5 = 12.5 − 3.5

Simplify.

4 y = 9

Undo multiplication. Divide each side by 4 .

4 y 4 = 9 4

Simplify.

y = 2.25

To check the solution, substitute 2.25 for y in the equation.

4 ( 2.25 ) + 3.5 = ? 12.25

Simplify.

4 ( 2.25 ) + 3.5 = ? 12.25                           9 + 3.5 = ? 12.25                                   12.5 = 12.5