The question is 1/3 ( x + 9 ) = 12. You want to find out the value of x.

The way I sometimes teach the idea behind solving an equation is to first walk through it step-by-step in words:

1. This statement is telling you that one-third of the value of x + 9 is equal to 12. Let's call
x + 9 an expression.

2. If one third of any expression is equal to 12, then the entire expression must be equal to 36 (because you need three thirds to get to a whole, and 3 times 12 will get you to 36, won't it?) So now we've gotten rid of the 1/3 part and can just say x + 9 is equal to 36.

3. If 9 and something is equal to 36, we can take 9 away from 36 to find out what that is (real quick, take ten away from 36 and then add one back).

Alejandra K. | Tutoring elementary mathematics! Tutoring elementary mathematics!

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You need to do the reciprocal of 1/3 and multiply it to the other side. That will give you 36. so your equation will look like this x+9=36. Then subtract the 9 from the 36. And you will get x=27.

You can check your answer by plugging in the 27 in the original equation. 1/3((27)+9)=12. Your answer will be 12=12 which indicates that your answer is correct!