Solve for r
r=-\frac{8}{3\pi }\approx -0.848826363
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3\pi r=1-9
Subtract 9 from both sides.
3\pi r=-8
Subtract 9 from 1 to get -8.
\frac{3\pi r}{3\pi }=-\frac{8}{3\pi }
Divide both sides by 3\pi .
r=-\frac{8}{3\pi }
Dividing by 3\pi undoes the multiplication by 3\pi .
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