a)
\frac{-3^2*(-6)^{-1}}{\sqrt{1-\frac{16}{25}}}=\frac{-\not9^3*(-\frac{1}{\not6^2})}{\sqrt{\frac{25}{25}-\frac{16}{25}}}=\frac{\frac{3}{2}}{\sqrt{\frac{9}{25}}}=\frac{\frac{3}{2}}{\frac{3}{5}}=\frac{\not3^1}{2}*\frac{5}{\not3^1}=\frac{5}{2}=2\frac{1}{2}=2,5
b)
\frac{\sqrt{1\frac{9}{16}}-(-2)^2:1\frac{1}{3}}{-5}=\frac{\sqrt{\frac{25}{16}}-4:\frac{4}{3}}{-5}=\frac{\frac{5}{4}-4*\frac{3}{4}}{-5}=\frac{\frac{5}{4}-\frac{12}{4}}{-5}=\frac{-\frac{7}{4}}{-5}=\frac{7}{4}*\frac{1}{5}=\frac{7}{20}
c)
\frac{\sqrt[3]{\frac{27}{8}}*\sqrt{\frac{4}{9}}}{5^{-2}*125}=\frac{\frac{\not3^1}{\not2^1}*\frac{\not2^1}{\not3^1}}{5^{-2}*5^3}=\frac{1}{5^{-2+3}}=\frac{1}{5}