83. Вычислите значение выражения: 1) (2 1/4 + 3 2/3) : (8 1/2 − 1 2/5) · 1,2; 2) (1 9/16 · 3 1/5 + 1 2/3 − 9 : 2 2/5) : (17 7/12 − 6 1/3).

1. \(2\frac14+3\frac23=\frac94+\frac{11}{3}=\frac{51}{12}=\frac{17}{4}\).
   \(8\frac12-1\frac25=\frac{17}{2}-\frac75=\frac{71}{10}\), а \(1,2=\frac65\).
   \(\frac{17}{4}:\frac{71}{10}\cdot\frac65=\frac{17}{4}\cdot\frac{10}{71}\cdot\frac65=\frac{51}{71}\).
2. \(1\frac{9}{16}\cdot3\frac15=\frac{25}{16}\cdot\frac{16}{5}=5\).
   \(9:2\frac25=9:\frac{12}{5}=\frac{15}{4}\).
   Числитель: \(5+1\frac23-\frac{15}{4}=5+\frac53-\frac{15}{4}=\frac{17}{12}\).
   Знаменатель: \(17\frac{7}{12}-6\frac13=\frac{211}{12}-\frac{76}{12}=\frac{135}{12}=\frac{45}{4}\).
   \(\frac{17}{12}:\frac{45}{4}=\frac{17}{12}\cdot\frac4{45}=\frac{17}{135}\).

Ответ: 1) \(\frac{51}{71}\); 2) \(\frac{17}{135}\).