15) 3ab ⋅ (-3ab²) ⋅ $$ \frac{4}{3} $$a = 3 ⋅ (-3) ⋅ $$ \frac{4}{3} $$ ⋅ a ⋅ a ⋅ a ⋅ b ⋅ b² = -12a³b³
Ответ: -12a³b³