12) $$ \frac{8}{9} $$ak ⋅ $$ \frac{9}{2} $$a²k² = $$ \frac{8}{9} $$ ⋅ $$ \frac{9}{2} $$ ⋅ a ⋅ a² ⋅ k ⋅ k² = 4a³k³
Ответ: 4a³k³