$\"\"$

The given expression is $\"\"$ .

Method 1: Horizontally addition.

$\"\"$

$\"\"$ (Group the like terms)

Combine like terms using distributive property: ac $\"\"$ bc = (a $\"\"$ b)c.

$\"\"$

Method 2: Vertically addition.

The given terms are in descending order and like terms are aligned.

$\"\"$

$\"\"$ $\"\"$

The sum of the expression is $\"\"$ .