## Geometry: Common Core (15th Edition)

$x = 53$
If $a | | b$, then alternate interior angles are equal. Let us set the two alternate interior angles equal to one another: $2x + 18 = 124$ Subtract $18$ from each side of the equation to isolate the $x$ term to one side of the equation and the constants on the other: $2x = 124 - 18$ $2x = 106$ Divide each side by $2$ to solve for $x$: $x = 53$