80. Выполните вычитание: 1) 4 3/16 − 5/8; 2) 6 4/9 − 3 6/7; 3) 10 11/24 − 8 19/36; 4) 9 1/6 − 5 3/4.

1. \(4\frac{3}{16}-\frac{5}{8}=3\frac{19}{16}-\frac{10}{16}=\mathbf{3\frac{9}{16}}\).
2. \(6\frac{4}{9}-3\frac{6}{7}=5\frac{91}{63}-3\frac{54}{63}=\mathbf{2\frac{37}{63}}\).
3. \(10\frac{11}{24}-8\frac{19}{36}=9\frac{105}{72}-8\frac{38}{72}=\mathbf{1\frac{67}{72}}\).
4. \(9\frac{1}{6}-5\frac{3}{4}=8\frac{14}{12}-5\frac{9}{12}=\mathbf{3\frac{5}{12}}\).

Ответ: 1) 3 9/16; 2) 2 37/63; 3) 1 67/72; 4) 3 5/12.