\begin{gathered}-2,5\sqrt{75}=-2,4\cdot \sqrt{25\cdot 3}=-2,4\cdot 5\sqrt3=-12\sqrt3-100\sqrt{0,08}=-100\sqrt{0,2^2\cdot 0,2}=-100\cdot 0,2\cdot \sqrt{0,2}=-20\sqrt{0,2}dfrac{2}{3}\sqrt{6\dfrac{3}{4}}=\dfrac{2}{3}\sqrt{ \dfrac{27}{4}}=\dfrac{2}{3}\sqrt{\dfrac{3^2\cdot 3}{2^2}}=\dfrac{2}{3}\cdot \dfrac{3}{2}}\cdot \sqrt3=\sqrt3\end{gathered}
\begin{gathered}-2,5\sqrt{75}=-2,4\cdot \sqrt{25\cdot 3}=-2,4\cdot 5\sqrt3=-12\sqrt3-100\sqrt{0,08}=-100\sqrt{0,2^2\cdot 0,2}=-100\cdot 0,2\cdot \sqrt{0,2}=-20\sqrt{0,2}dfrac{2}{3}\sqrt{6\dfrac{3}{4}}=\dfrac{2}{3}\sqrt{ \dfrac{27}{4}}=\dfrac{2}{3}\sqrt{\dfrac{3^2\cdot 3}{2^2}}=\dfrac{2}{3}\cdot \dfrac{3}{2}}\cdot \sqrt3=\sqrt3\end{gathered}