ANSWER:
[tex]\frac{1}{576x^7y^7}[/tex]STEP-BY-STEP EXPLANATION:
We have the following function:
[tex]\frac{\left(72x^{-1}y^4\right)^{-1}}{8x^8y^3}[/tex]We operate to simplify and we are left with the following:
[tex]\frac{72^{-1}x^{-1\cdot-1}y^{4\cdot-1}}{8x^8y^3}=\frac{\frac{1}{72}xy^{-4}}{8x^8y^3}=\frac{1}{72\cdot8\cdot x^8\cdot x^{-1}\cdot y^3\cdot y^4}=\frac{1}{576x^7y^7}[/tex]