Answer:
[tex]\large\boxed{y^{-3}\cdot y^6=y^3}[/tex]
Step-by-step explanation:
[tex]y^{-3}\cdot y^6\qquad\text{use}\ a^n\cdot a^m=a^{n+m}\\\\=y^{-3+6}=y^3[/tex]
