Answer:
[tex]\frac{27}{8}[/tex]
Step-by-step explanation:
[tex]\left(\frac{16}{81}\right)^{\frac{-3}{4}}=\frac{16^{\frac{-3}{4}}}{81^{\frac{-3}{4}}}[/tex]
[tex]=\frac{2^{-3} }{3^{-3} }[/tex]
[tex]=\frac{\frac{1}{8}}{\frac{1}{27}}[/tex]
[tex]=\frac{1*27}{8*1}[/tex]
[tex]=\frac{27}{8}[/tex]