$\"\"$

The expression is $\"\"$ .

Add the polynomials horizontally

$\"\"$ (Remove brackets)

$\"\"$ (Apply commutative property of addition: $\"\"$ )

$\"\"$ (Subtract: $\"\"$ )

$\"\"$ (Apply commutative property of addition: $\"\"$ )

$\"\"$ (Subtract: $\"\"$ ) $\"\"$

The sum of polynomials is $\"\"$ .