Solve for r
r=\frac{12}{13}\approx 0.923076923
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8r-3+5r=9
Add 5r to both sides.
13r-3=9
Combine 8r and 5r to get 13r.
13r=9+3
Add 3 to both sides.
13r=12
Add 9 and 3 to get 12.
r=\frac{12}{13}
Divide both sides by 13.
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