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

\frac{6}{5} - (b + \frac{2}{3}) = \frac{1}{3}\\\-b - \frac{2}{3} = \frac{1}{3} - \frac{6}{5}\\\-b = \frac{1}{3} - \frac{6}{5} + \frac{2}{3}\\\-b = \frac{5}{15} - \frac{18}{15} + \frac{10}{15}\\\-b = -\frac{3}{15}\\\-b = -\frac{1}{5}\\b = \frac{1}{5} Ответ: \frac{1}{5}