Solve for r
r=\frac{1}{3}\approx 0.333333333
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15r=12-\left(2\times 3+1\right)
Multiply both sides of the equation by 3.
15r=12-\left(6+1\right)
Multiply 2 and 3 to get 6.
15r=12-7
Add 6 and 1 to get 7.
15r=5
Subtract 7 from 12 to get 5.
r=\frac{5}{15}
Divide both sides by 15.
r=\frac{1}{3}
Reduce the fraction \frac{5}{15} to lowest terms by extracting and canceling out 5.
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