$\"\"$

First determine the equal measures:

$\"\"$ and $\"\"$

The perimeter is given by 32 units.

$\"\"$ (Apply definition of perimeter) $\"\"$ (Substitute $\"\"$ ) $\"\"$ (Substitute $\"\"$ and $\"\"$ ) $\"\"$ (Simplify)

$\"\"$

$\"\"$ (Subtract 12 from each side)

$\"\"$ (Simplify)

$\"\"$ (Subtract)

$\"\"$ (Divide each side by 4)

$\"\"$ (Simplify)

$\"\"$ (Divide) $\"\"$

The value of $\"\"$ .