3) $$\frac{6}{5} - (\frac{2}{3} + b) = \frac{1}{3}$$

$$\frac{6}{5} - (\frac{2}{3} + b) = \frac{1}{3}$$ $$\frac{6}{5} - \frac{2}{3} - b = \frac{1}{3}$$ $$\frac{6}{5} - \frac{2}{3} - \frac{1}{3} = b$$ $$\frac{6}{5} - \frac{3}{3} = b$$ $$\frac{6}{5} - 1 = b$$ $$\frac{6}{5} - \frac{5}{5} = b$$ $$\frac{1}{5} = b$$ $$b = \frac{1}{5}$$ Ответ: $$b = \frac{1}{5}$$