1. Вычислите: \(\frac{7}{9} - \frac{5}{6} : \frac{4}{15}\) Ответ:

1. Вычислим: $$ \frac{7}{9} - \frac{5}{6} : \frac{4}{15} = \frac{7}{9} - \frac{5}{6} \cdot \frac{15}{4} = \frac{7}{9} - \frac{5 \cdot 15}{6 \cdot 4} = \frac{7}{9} - \frac{75}{24} = \frac{7}{9} - \frac{25}{8} = \frac{7 \cdot 8}{9 \cdot 8} - \frac{25 \cdot 9}{8 \cdot 9} = \frac{56}{72} - \frac{225}{72} = \frac{56 - 225}{72} = \frac{-169}{72} = -2\frac{25}{72} $$

Ответ: -2$$\frac{25}{72}$$