Answer
$\frac{y^{2}}{27x^{12}}$
Work Step by Step
Start with the given expression: $(\frac{3x^{4}}{y})^{-3}$
Use negative exponent rule to invert fraction: $(\frac{y}{3x^{4}})^{3}$
Remove the parentheses: $\frac{y^{3}}{3^{3}(x^{4})^{3}}$
Use power rule to simplify denominator: $\frac{y^{2}}{27x^{12}}$
