a: \(\dfrac{5}{6}-0,75+50\%\)
\(=\dfrac{5}{6}-\dfrac{3}{4}+\dfrac{1}{2}\)
\(=\dfrac{5}{6}-\dfrac{1}{4}=\dfrac{10}{12}-\dfrac{3}{12}=\dfrac{7}{12}\)
b: \(\dfrac{-2}{5}\cdot\dfrac{4}{11}+0,4\cdot\dfrac{-6}{11}-\dfrac{1}{11}:\dfrac{5}{2}\)
\(=\dfrac{-2}{5}\cdot\dfrac{4}{11}+\dfrac{2}{5}\cdot\dfrac{-6}{11}-\dfrac{1}{11}\cdot\dfrac{2}{5}\)
\(=-\dfrac{2}{5}\left(\dfrac{4}{11}+\dfrac{6}{11}+\dfrac{1}{11}\right)\)
\(=-\dfrac{2}{5}\cdot\dfrac{11}{11}=-\dfrac{2}{5}\)
c: \(\dfrac{-23}{17}-\dfrac{5}{39}-\left(-\dfrac{6}{17}+\dfrac{34}{39}\right)+2,54\)
\(=-\dfrac{23}{17}-\dfrac{5}{39}+\dfrac{6}{17}-\dfrac{34}{39}+2,54\)
\(=-\dfrac{17}{17}-\dfrac{39}{39}+2,54\)
=2,54-2
=0,54
d: \(3,25-4,5:\left(\dfrac{15}{4}-1\dfrac{1}{2}\right)-\left(-\dfrac{3}{2}\right)^2\)
\(=3,25-4,5:\left(3,75-3,5\right)-\dfrac{9}{4}\)
\(=1-4,5:0,25=1-18=-17\)
