Solve for x
x=3
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21-2x=15
Swap sides so that all variable terms are on the left hand side.
-2x=15-21
Subtract 21 from both sides.
-2x=-6
Subtract 21 from 15 to get -6.
x=\frac{-6}{-2}
Divide both sides by -2.
x=3
Divide -6 by -2 to get 3.
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