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

$\"\"$

Apply addition property of equality: Add 3x to each side.

$\"\"$

Rearrange the terms using commutative property: $\"\"$ .

$\"\"$

$\"\"$ (Apply additive inverse property: $\"\"$ )

$\"\"$ (Apply additive identity property: $\"\"$ ) $\"\"$

$\"\"$ (Substitute $\"\"$ )

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

$\"\"$ (Subtract: 12 – 27 = –15)

$\"\"$

The value of $\"\"$ .