$\text{a)}\frac{1\frac{3}{7}\cdot \left(-\frac{7}{10}\right)-4\frac{2}{5}:2\frac{1}{5}}{3\frac{2}{9}-\frac{4}{9}}=\frac{\frac{{\sout{10}}^1}{{\sout{7}}^1}\cdot \left(-\frac{{\sout{7}}^1}{{\sout{10}}^1}\right)-\frac{22}{5}:\frac{11}{5}}{2\frac{11}{9}-\frac{4}{9}}=\frac{-1-\frac{{\sout{22}}^2}{{\sout{5}}^1}\cdot \frac{{\sout{5}}^1}{{\sout{11}}^1}}{2\frac{7}{9}}=$  

$=\frac{-1-2}{\frac{25}{9}}=-3\cdot \frac{9}{25}=-\frac{27}{25}=-1\frac{2}{25}=-1\frac{8}{100}=-1,08$