## Geometry: Common Core (15th Edition)

$x = 18$
In a rhombus, diagonals bisect opposite angles. In this diagram, we have an angle bisected by the diagonal, so we can set the two expressions for the two angles equal to one another. $5x - 30 = 3x + 6$ Add $30$ to each side of the equation to move constants to the right side of the equation: $5x = 3x + 36$ Subtract $3x$ from each side of the equation to move variables to the left side of the equation: $2x = 36$ Divide each side by $2$ to solve for $x$: $x = 18$