5) \(\frac{12}{20}\cdot3\)

Сократим дробь:

\(\frac{12}{20}=\frac{3}{5}\).

\(\frac{3}{5}\cdot3=\frac{9}{5}=1\frac{4}{5}\).

Ответ: \(\frac{9}{5}=1\frac{4}{5}\).