1. Сократите: 9/15, 8/56, 42/90, (38·18)/(9·19).

1. \(\frac{9}{15}=\frac{9:3}{15:3}=\frac{3}{5}\).
2. \(\frac{8}{56}=\frac{8:8}{56:8}=\frac{1}{7}\).
3. \(\frac{42}{90}=\frac{42:6}{90:6}=\frac{7}{15}\).
4. \(\frac{38\cdot18}{9\cdot19}=\frac{2\cdot19\cdot2\cdot9}{9\cdot19}=4\).

Ответ: \(\frac{3}{5};\ \frac{1}{7};\ \frac{7}{15};\ 4\).