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3 - x = 12

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2 Answers

You can move -x to the right side of the = and 12 to the left side of the equal. After you do that, this becomes.

3-12= x

Notice when you move, this changes the + or - sign.

so x = -9

 

Ok, we need to isolate x and there are two ways to do this. First, subtract 3 from both sides.

-3 + 3 - x = 12 - 3.

The two 3's on the left cancel and we have

-x = 9

Now, we multiply both sides by -1 so that x is by itself and we have x = -9!

Comments

Don't forget to check your work!

3-x=12 if x= -9

3-(-9)=12

any time I see a -(- i look at it as if it was a + because thats essentially what you have to do. 

so 3 + 9 = 12

12=12 CHECKS OUT! way to go.

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