e) - \frac{5}{8} + \frac{5}{6};

e) - \frac{5}{8} + \frac{5}{6} = - \frac{5 \cdot 3}{8 \cdot 3} + \frac{5 \cdot 4}{6 \cdot 4} = - \frac{15}{24} + \frac{20}{24} = \frac{20 - 15}{24} = \frac{5}{24}