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

The expression is $\"\"$

$\"\"$ (Distribute 3)

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

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

$\"\"$

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

$\"\"$ (Distribute x)

$\"\"$ (Add: $\"\"$ ) $\"\"$

The simplified expression is $\"\"$ .