Решение:
\[ \frac{2}{3} \times \frac{1}{3}x - \frac{2}{3} \times \frac{1}{2} = 4x + 2,5 \]
\[ \frac{2}{9}x - \frac{1}{3} = 4x + 2,5 \]
\[ \frac{2}{9}x - \frac{1}{3} = 4x + 2,5 \]
\[ -\frac{1}{3} - 2,5 = 4x - \frac{2}{9}x \]
\[ -\frac{1 \times 3}{3 \times 3} - \frac{2,5 \times 9}{9} = \frac{4 \times 9}{9}x - \frac{2}{9}x \]
\[ -\frac{3}{9} - \frac{22,5}{9} = \frac{36}{9}x - \frac{2}{9}x \]
\[ -\frac{25,5}{9} = \frac{34}{9}x \]
\[ x = -\frac{25,5}{9} \times \frac{9}{34} \]
\[ x = -\frac{25,5}{34} \]
\[ x = -0,75 \]
Ответ: x = -0,75