TeX джерело:

\left\{ \begin{array}{l}{2^x} \cdot {3^y} \cdot {2^y} \cdot {3^x} = 12 \cdot 18,\\\frac{{{2^x} \cdot {3^y}}}{{{2^y} \cdot {3^x}}} = \frac{{12}}{{18}}.\end{array} \right.\;\left\{ \begin{array}{l}{6^{x + y}} = 216,\\{(\frac{2}{3})^{x - y}} = \frac{2}{3};\end{array} \right.\;\left\{ \begin{array}{l}x + y = 3,\\x - y = 1;\end{array} \right.\;\left\{ \begin{array}{l}2x = 4,\\2y = 2;\end{array} \right.\;\left\{ \begin{array}{l}x = 2,\\y = 1.\end{array} \right.