\[\boxed{\text{4.\ 247}}\]
\[\textbf{а)} - x = 4,5\]
\[x = - 4,5.\]
\[\textbf{б)} - x = - \frac{4}{5}\]
\[x = \frac{4}{5}.\]
\[\textbf{в)} - y = - 3,8 + 5\]
\[- y = 1,2\]
\[y = - 1,2.\]
\[\textbf{г)} - y = - 8\frac{5}{7} + 7\frac{2}{7}\]
\[- y = - 1\frac{3}{7}\]
\[y = 1\frac{3}{7}.\]
\[\textbf{д)} - z = 22 + ( - 23,4)\]
\[- z = - 1,4\]
\[z = 1,4.\]
\[\textbf{е)} - z = - 72 + \left( - 9\frac{7}{3} \right)\]
\[- z = - 72 - 11\frac{1}{3}\]
\[- z = - 83\frac{1}{3}\]
\[z = 83\frac{1}{3}.\]