Solve for r
r = \frac{20}{7} = 2\frac{6}{7} \approx 2.857142857
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2r+5r=20
Multiply both sides of the equation by 10, the least common multiple of 5,2.
7r=20
Combine 2r and 5r to get 7r.
r=\frac{20}{7}
Divide both sides by 7.
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