SOLUTION: when solving 3x + 6 = 18, why do you add -6 under the 6 which makes 0 and add -6 under the 18, which makes 12? then it turns out to be 3x = 12, and x = 4. The problem I am having

Algebra ->  Signed-numbers -> SOLUTION: when solving 3x + 6 = 18, why do you add -6 under the 6 which makes 0 and add -6 under the 18, which makes 12? then it turns out to be 3x = 12, and x = 4. The problem I am having       Log On


   

Question 530055: when solving 3x + 6 = 18, why do you add -6 under the 6 which makes 0 and add -6 under the 18, which makes 12? then it turns out to be 3x = 12, and x = 4. The problem I am having is the signs, why do you use the negative 6?
Answer by rfer(16322) About Me  (Show Source):
You can put this solution on YOUR website!
In order to remove the 6 from the left side it is necessary to do the opposite of what is there. In this case it is a +6 so you need to subtract to remove it.
In equations it is always necessay to do the same thing to both sides, thus 18-6=12.
Another thought, if you had 3x-6=18 you would add 6 to both sides to remove it from the left side. Always do the opposite to what is there.
Does that help?
Bob