1.4. Вычислите: \(\frac{1}{4}-\frac{9}{20}\).

\(\frac{1}{4}=\frac{5}{20}\).

\(\frac{5}{20}-\frac{9}{20}=-\frac{4}{20}=-\frac{1}{5}\).

Ответ: \(-\frac{1}{5}\).