Solve for u
u=-2
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2u+9-8u=21
Subtract 8u from both sides.
-6u+9=21
Combine 2u and -8u to get -6u.
-6u=21-9
Subtract 9 from both sides.
-6u=12
Subtract 9 from 21 to get 12.
u=\frac{12}{-6}
Divide both sides by -6.
u=-2
Divide 12 by -6 to get -2.
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