\[\boxed{\text{4.\ 360}}\]
\[\textbf{а)} - \frac{1}{8} + \frac{3}{16} = - \frac{2}{16} + \frac{3}{16} = \frac{1}{16}\]
\[\textbf{б)}\ 4,8 - 5,9 = - 1,1 = - \frac{11}{10}\]
\[\textbf{в)} - \frac{4}{9} \cdot 1\frac{7}{11} = - \frac{4}{9} \cdot \frac{18}{11} = - \frac{8}{11}\]
\[\textbf{г)} - 4,8 \cdot ( - 1,4) = \frac{48}{14} = \frac{24}{7}\]
\[\textbf{д)} - 1,25\ :( - 0,25) = \frac{125}{25} = \frac{5}{1}\]
\[\textbf{е)} - 1,6\ :( - 1,2) = \frac{16}{12} = \frac{4}{3}\ \]