Solve for r
r=-4
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2r+1=-7
Swap sides so that all variable terms are on the left hand side.
2r=-7-1
Subtract 1 from both sides.
2r=-8
Subtract 1 from -7 to get -8.
r=\frac{-8}{2}
Divide both sides by 2.
r=-4
Divide -8 by 2 to get -4.
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