14) \(\frac{9}{20} - \frac{11}{30}\)

Решение:

\(\frac{9}{20} - \frac{11}{30} = \frac{9 \cdot 3}{20 \cdot 3} - \frac{11 \cdot 2}{30 \cdot 2} = \frac{27}{60} - \frac{22}{60} = \frac{27-22}{60} = \frac{5}{60} = \frac{1}{12}\)

Ответ: \(\frac{1}{12}\)