$a)$  

$w\left(-2,3\right)=\frac{1}{3}\cdot {\left(-2\right)}^2\cdot 3^3-3\cdot \left(-2\right)\cdot 3^2+{\left(-2\right)}^3\cdot 3=$   

$=\frac{1}{\sout{3}}\cdot 4\cdot {\sout{27}}^9+6\cdot 9+\left(-8\right)\cdot 3=$   $36+54-24=66$