\[\boxed{\mathbf{П.\ 27}}\]
\[\textbf{а)}\ 4z + 23,5 = 3z\]
\[4z - 3z = 23,5\]
\[z = 23,5.\ \]
\[\textbf{б)} - 5z = 13\frac{1}{8}\]
\[z = \frac{105}{8}\ :( - 5) = - \frac{105}{8} \cdot \frac{1}{5}\]
\[z = - \frac{17}{8} = - 2\frac{1}{8}.\]