$\"\"$

\

The polynomial is $\"\"$ .

\

Horizontal method:

\

Subtract $\"\"$ by adding its additive inverse.

\

The additive inverse of $\"\"$ is $\"\"$ .

\

$\"\"$

\

Group like terms.

\

$\"\"$

\

Combine like terms.

\

$\"\"$ . $\"\"$

\

The value of $\"\"$ .