53. Решите уравнение: 1) 8 3/4 − x = 3 5/16; 2) (x − 9 3/7) + 5 8/21 = 6 5/14.

1. \(8\frac{3}{4}-x=3\frac{5}{16}\)
   \(x=8\frac{3}{4}-3\frac{5}{16}=8\frac{12}{16}-3\frac{5}{16}=5\frac{7}{16}\).
2. \((x-9\frac{3}{7})+5\frac{8}{21}=6\frac{5}{14}\)
   \(x-9\frac{3}{7}=6\frac{5}{14}-5\frac{8}{21}=6\frac{15}{42}-5\frac{16}{42}=\frac{41}{42}\).
   \(x=9\frac{3}{7}+\frac{41}{42}=9\frac{18}{42}+\frac{41}{42}=10\frac{17}{42}\).

Ответ: 1) \(x=5\frac{7}{16}\); 2) \(x=10\frac{17}{42}\).