X is -8
To solve the problem you have to get X by itself. So you would multiply every number in the equation by 4. Which will give you -X + 12 = 20
Now you have to subtract 12 on both sides of the equal side giving you -X = 8 since the positive twelve cancels out.
Finally you divide by negative 1 since X can NOT be a negative!
Your final answer should be X = -8
I hope that helped and you know what to do now...