There are a few rules to work with here...first:
a^b/(a^c)=a^(b-c) so for the part in the parentheses the y terms become:
(y^-3/(8x^6))^(-1/3)
and y^-3=1/y^3 so we have
(1/(8x^6*y^3))^(-1/3)
The other rule is that a^(-b)=1/a^b so we can just flip the fraction...
(8y^3*x^6)^(1/3) since everything inside is a perfect cube...
2yx^2