help solve the above equation

Answer:
[tex]\dfrac{1}{27}[/tex]
Step-by-step explanation:
[tex]n^{-\frac{2}{3}}=9[/tex]
Rewrite:
[tex]\dfrac{1}{\sqrt[3]{n^2}}=9\\\\9\sqrt[3]{n^2}=1[/tex]
Cube both sides:
[tex]729n^2=1[/tex]
Divide both sides by 729:
[tex]n^2=\dfrac{1}{729}[/tex]
Take the square root of both sides:
[tex]n=\sqrt{\dfrac{1}{729}}=\dfrac{1}{27}[/tex]
Hope this helps!