Distribute 4 through the parentheses.
4x + 12 = 4x + 12
Subtract 12 from both sides.
4x + 12 - 12 = 4x + 12 - 12
Subtract twice.
4x = 4x
Subtract 4x again.
4x - 4x = 4x - 4x
The answer is 0.
