83. Вычислите значение выражения:

Решение:

1. \( \left( 2 \frac{1}{4} + 3 \frac{2}{3} \right) : \left( 8 \frac{1}{2} - 1 \frac{2}{5} \right) \cdot 1,2 = \left( \frac{9}{4} + \frac{11}{3} \right) : \left( \frac{17}{2} - \frac{7}{5} \right) \cdot \frac{6}{5} = \left( \frac{27+44}{12} \right) : \left( \frac{85-14}{10} \right) \cdot \frac{6}{5} = \frac{71}{12} : \frac{71}{10} \cdot \frac{6}{5} = \frac{71}{12} \cdot \frac{10}{71} \cdot \frac{6}{5} = \frac{1}{12} \cdot 10 \cdot \frac{6}{5} = \frac{10}{12} \cdot \frac{6}{5} = \frac{5}{6} \cdot \frac{6}{5} = 1 \)
2. \( \left( 1 \frac{9}{16} \cdot 3 \frac{1}{5} + 1 \frac{2}{3} - 9 \frac{2}{5} \right) : \left( 17 \frac{7}{12} - 6 \frac{1}{3} \right) = \left( \frac{25}{16} \cdot \frac{16}{5} + \frac{5}{3} - \frac{47}{5} \right) : \left( \frac{211}{12} - \frac{19}{3} \right) = \left( 5 + \frac{5}{3} - \frac{47}{5} \right) : \left( \frac{211-76}{12} \right) = \left( \frac{75+25-141}{15} \right) : \frac{135}{12} = \frac{-41}{15} : \frac{45}{4} = \frac{-41}{15} \cdot \frac{4}{45} = \frac{-164}{675} \)

Ответ: 1) \( 1 \); 2) \( -\frac{164}{675} \).