Answer: -3x + 7
Step-by-step explanation: All you have to do is combine like terms
First, you combine 3x - 6x which, will give you -3x
Second, you combine 12 - 5 which will give you 7
3x - 6x = -3x
12 - 5 = 7
So, combine the answers and you will get -3x + 7