what is 27/64 to the negative 4/3 power?

(27/64) ^(-4/3)  =

(64/27) ^ (4/3)   =

[(64/27)^(1/3)]^4   =

[ 4/3 ]^4  =

256 / 81

$({27\over64})^{-{4\over3}}={256\over81}=3.1604938271604937$

$( \frac{27}{64})^{- \frac{4}{3}} = ( \frac{27*27^{1/3}}{64*64^{1/3}})^{-1} = ( \frac{27*3}{64*4} )^{-1}= \frac{256}{81}$