First, solve the parenthesis by multiplying the numbers in and out of them:
2+6x-12=12x-6
Next, put them in order so you can solve the equation:
2-12+6=-6x+12x
Next solve:
-4=6x
So x is:
-6/4
So C is the correct answer,
Hopefully, this helps you find the answer! If it doesn't, tell me in the space below and I'll solve it completely