Solve for r
r=3
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-9-6r=-9r
Combine -2r and -7r to get -9r.
-9-6r+9r=0
Add 9r to both sides.
-9+3r=0
Combine -6r and 9r to get 3r.
3r=9
Add 9 to both sides. Anything plus zero gives itself.
r=\frac{9}{3}
Divide both sides by 3.
r=3
Divide 9 by 3 to get 3.
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