a: \(0,25\cdot1\dfrac{3}{5}\cdot\left(\dfrac{5}{4}\right)^2:\left(-\dfrac{4}{7}\right)\)
\(=\dfrac{1}{4}\cdot\dfrac{8}{5}\cdot\dfrac{25}{16}\cdot\dfrac{-7}{4}\)
\(=\dfrac{2}{5}\cdot\dfrac{25}{16}\cdot\dfrac{-7}{4}=\dfrac{50}{80}\cdot\dfrac{-7}{4}=-\dfrac{7}{4}\cdot\dfrac{5}{8}=-\dfrac{35}{32}\)
b: \(\left(14-12\dfrac{1}{3}\right)\cdot4,5-7\dfrac{2}{3}:\left(8-5,75\right)\)
\(=\left(14-12-\dfrac{1}{3}\right)\cdot4,5-\dfrac{23}{3}:2,25\)
\(=\dfrac{7}{3}\cdot4,5-\dfrac{23}{3}:\dfrac{9}{4}\)
\(=\dfrac{7}{3}\cdot\dfrac{9}{2}-\dfrac{23}{3}\cdot\dfrac{4}{9}=\dfrac{21}{2}-\dfrac{92}{27}=\dfrac{383}{54}\)
c: \(\left(25\%+\dfrac{1}{3}+0,75\right):\left(4\dfrac{3}{4}-3\dfrac{1}{2}\right)\)
\(=\left(0,25+\dfrac{1}{3}+0,75\right):\left(4+\dfrac{3}{4}-3-\dfrac{1}{2}\right)\)
\(=\dfrac{4}{3}:\left(1+\dfrac{1}{4}\right)=\dfrac{4}{3}:\dfrac{5}{4}=\dfrac{4}{3}\cdot\dfrac{4}{5}=\dfrac{16}{15}\)
