\ANG{
Vereinfache: 
\[\text{(a)}\quad\left[\frac{a^2 (bc)^4}{(ab)^4 c^3}\right] \cdot
\left[\frac{a^5 b^0 c^2}{a^7 c^6}\right]^3\qquad
\text{(b)}\quad\left[ \left( \frac{\D 2a^{-1}b^2}{\D 3a^5c^{-3}} \right)^3:
\left( \frac{\D 3 a^6 b^{-4}}{\D 7a^{-2}c^4} \right)^{-2} \right] \cdot
\left( \frac{\D - c^0}{\D 7a} \right)^{-1}\]
}
\LSG{
(a)\quad$a^{-8}c^{-11}$\qquad (b)\quad$-\frac{\D 8c}{\D 21ab^2}$
}