$\"\"$

Let $\"\"$ , $\"\"$ , $\"\"$ and $\"\"$ .

$\"\"$ (Segment product)

$\"\"$ (Substitute $\"\"$ , $\"\"$ , $\"\"$ and $\"\"$ )

$\"\"$ (Multiply: $\"\"$ ) $\"\"$

$\"\"$ (Divide each side by 9)

$\"\"$ (Cancel common terms)

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

The value of $\"\"$ .