Solve for r
r=-30
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\frac{1}{2}r=-27+12
Add 12 to both sides.
\frac{1}{2}r=-15
Add -27 and 12 to get -15.
r=-15\times 2
Multiply both sides by 2, the reciprocal of \frac{1}{2}.
r=-30
Multiply -15 and 2 to get -30.
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