Two-Step Equations

Undo addition/subtraction first, then multiplication/division:

$2x + 5 = 13$ $2x = 8$ $x = 4$

$\frac{x}{3} - 4 = 2$ $\frac{x}{3} = 6$ $x = 18$

Equations with Negative Numbers

$-3x + 9 = 0$ $-3x = -9$ $x = 3$

Checking Your Solution

Always substitute back: If $x = 4$ in $2x + 5 = 13$: $2(4) + 5 = 8 + 5 = 13$ ✓

Writing Equations from Words

Golden rule: Whatever you do to one side, do to the other. Keep the equation balanced!