1. Сократи: 12/18, 6/54, 56/98, (42·24)/(8·21).

\(\frac{12}{18}=\frac{12:6}{18:6}=\frac{2}{3}\).

\(\frac{6}{54}=\frac{6:6}{54:6}=\frac{1}{9}\).

\(\frac{56}{98}=\frac{56:14}{98:14}=\frac{4}{7}\).

\(\frac{42\cdot24}{8\cdot21}=\frac{42}{21}\cdot\frac{24}{8}=2\cdot3=6\).