w=2\frac{1}{7}=\frac{15}{7} \ feet \\ \\ A=L*w \\ A=9 \ feet^2 \\ \\ L*\frac{15}{7}=9 \\ \\ \frac{15L}{7}=9 \\ \\ L=\frac{7*9}{15}=\frac{7*3}{5} \\ \\ \boxed{L=\frac{21}{5} feet}