a) \(\frac{15^5.10^5}{6^6.25^6}\)= (15.10)^5/(6.25)^6=150^5/150^6=1/150
\(^{\frac{\left(5^4-5^3\right)^3}{125^4}=\frac{\left[5^3\cdot\left(5-1\right)\right]^3}{\left(5^3\right)^4}=\frac{\left[5^3\cdot4\right]^3}{5^3\cdot4}=\frac{\left(5^3\right)^3\cdot4^3}{5^{12}}=\frac{5^9\cdot4^3}{5^9\cdot5^3}=\frac{4^3}{5^3}}\)