Answer:
[tex]\large\boxed{5y^{-3}=\dfrac{5}{y^3}}[/tex]
Step-by-step explanation:
[tex]\text{Use}\ a^{-n}=\dfrac{1}{a^n}\\\\5y^{-3}=5\left(\dfrac{1}{y^3}\right)=\dfrac{5}{y^3}[/tex]