в) $$ \frac{-12d^4v^3}{48d^6v^7} = \frac{-12}{48} \cdot \frac{d^4}{d^6} \cdot \frac{v^3}{v^7} = -\frac{1}{4} \cdot d^{4-6} \cdot v^{3-7} = -\frac{1}{4} \cdot d^{-2} \cdot v^{-4} = -\frac{1}{4d^2v^4} $$
Ответ: $$\frac{-1}{4d^2v^4}$$