Solve for x
x=63
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3x-231=399-7x
Multiply both sides of the equation by 21, the least common multiple of 7,3.
3x-231+7x=399
Add 7x to both sides.
10x-231=399
Combine 3x and 7x to get 10x.
10x=399+231
Add 231 to both sides.
10x=630
Add 399 and 231 to get 630.
x=\frac{630}{10}
Divide both sides by 10.
x=63
Divide 630 by 10 to get 63.
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