Well, it would have to be -17 - 2x
Think about it: Look at the equation, 2x - 17. You notice that there's a " - 17" right? Well, that means that you have a negative number (-17). However, 2x stays the same, so you don't have to worry about that.
So, to make it easier, if you switch the equation around, you will have -17 - 2x