Since 4x and 3x are like terms, add 3x to 4x to get 7x.
7x+9=12-x-5
Subtract 5 from 12 to get 7.
7x+9=7-x
Since -x contains the variable to solve for, move it to the left-hand side of the equation by adding x to both sides.
7x+9+x=7
Since 7x and x are like terms, add x to 7x to get 8x.
8x+9=7
Since 9 does not contain the variable to solve for, move it to the right-hand side of the equation by subtracting 9 from both sides.
8x=-9+7
Add 7 to -9 to get -2.
8x=-2
Divide each term in the equation by 8.
(8x)/(8)=-(2)/(8)
Simplify the left-hand side of the equation by canceling the common factors.
x=-(2)/(8)
Simplify the right-hand side of the equation by simplifying each term.
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