Use the distributive property and administer the 6 to the parenthesis
This will give you 4n - 6n - 6 > 12
Add 6 to both sides giving you 4n - 6n > 18
Add the common factors together giving you -2n > 18, then divide both sides by 2
When you divide by a negative number in an equality you have to flip the sign
So your final answer is n<9
