в) $$\frac{5}{6} + \frac{3}{8} - \frac{1}{3} = \frac{5 \cdot 4}{6 \cdot 4} + \frac{3 \cdot 3}{8 \cdot 3} - \frac{1 \cdot 8}{3 \cdot 8} = \frac{20}{24} + \frac{9}{24} - \frac{8}{24} = \frac{20+9-8}{24} = \frac{21}{24} = \frac{7 \cdot 3}{8 \cdot 3} = \frac{7}{8}$$
Ответ: $$\frac{7}{8}$$