Solve for x
x=3
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3x-9+7x=21
Add 7x to both sides.
10x-9=21
Combine 3x and 7x to get 10x.
10x=21+9
Add 9 to both sides.
10x=30
Add 21 and 9 to get 30.
x=\frac{30}{10}
Divide both sides by 10.
x=3
Divide 30 by 10 to get 3.
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