Simplify:

$\left(ii\right)$ $15y^8÷3y^3$

Simplify the given expression $15y^8÷3y^3$

$=\frac{15y^8}{3y^3}$

$=5y^{8-3}$ $[\therefore \frac{a^m}{a^n}=a^{m-n}]$

$=5y^5$

Hence, $15y^8÷3y^3=5y^5$.