You can put this solution on YOUR website! I find that a minus sign is easier to deal with if I see it as part of the number that follows it. If I do not see a number, the number is an invisible 1. So for , I see . And for , I see .
For the problem above, I prefer to believe that I am seeing
I do not write it that way, but I see it that way in my mind, and that helps me keep the signs straight.
Otherwise, you have to remember (and hopefully justify to yourself) that to eliminate a set of brackets right after a minus sign, you also have to reverse all the signs inside the brackets, so that -(6x+2)=-(+6x+2) turns into .