a)\(\frac{4}{5}-\left(-\frac{2}{7}\right)-\frac{7}{10}=\frac{4}{5}+\frac{2}{7}-\frac{7}{10}\)
\(=\frac{56}{70}+\frac{20}{70}-\frac{49}{70}=\frac{56+20-49}{70}=\frac{27}{70}\)
b)\(\left(\frac{9}{25}-2.18\right):\left(3\frac{4}{5}+0,2\right)=\left(\frac{9}{25}-36\right):\left(\frac{19}{5}+\frac{1}{5}\right)\)
=\(\left(\frac{9}{25}-\frac{900}{25}\right):\frac{19+1}{5}=\frac{9-900}{25}:\frac{20}{5}\)
\(=\frac{-891}{25}.\frac{5}{20}=\frac{-891}{100}\)
c)\(\frac{3}{8}.19\frac{1}{3}-\frac{3}{8}.33\frac{1}{3}=\frac{3}{8}\left(19\frac{1}{3}-33\frac{1}{3}\right)=\frac{3}{8}\left[\left(19-33\right)+\left(\frac{1}{3}-\frac{1}{3}\right)\right]\)
\(=\frac{3}{8}.\left(-14\right)=\frac{21}{4}\)
d)\(4.\left(-\frac{1}{2}\right)^3-2.\left(-\frac{1}{2}\right)^2+3.\left(-\frac{1}{2}\right)+1\)
\(=4.\frac{\left(-1\right)^3}{2^3}-2\frac{\left(-1\right)^2}{2^2}+\frac{-3}{2}+1\)
\(=4.\frac{-1}{8}-2\frac{1}{4}+\frac{-3}{2}+1\)
\(=\frac{-1}{2}-\frac{1}{2}+\frac{-3}{2}+\frac{2}{2}=\frac{-1-1-3+2}{2}=\frac{-3}{2}\)
