Solve for k
k=10
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8k-9-5k=21
Subtract 5k from both sides.
3k-9=21
Combine 8k and -5k to get 3k.
3k=21+9
Add 9 to both sides.
3k=30
Add 21 and 9 to get 30.
k=\frac{30}{3}
Divide both sides by 3.
k=10
Divide 30 by 3 to get 10.
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