50. Найдите сумму:

Решение:

1. \( 12\frac{1}{8} + 8\frac{1}{6} = \frac{12 \cdot 8 + 1}{8} + \frac{8 \cdot 6 + 1}{6} = \frac{97}{8} + \frac{49}{6} = \frac{97 \cdot 3}{24} + \frac{49 \cdot 4}{24} = \frac{291 + 196}{24} = \frac{487}{24} = 20\frac{7}{24} \)
2. \( 3\frac{13}{15} + 6\frac{7}{10} = \frac{3 \cdot 15 + 13}{15} + \frac{6 \cdot 10 + 7}{10} = \frac{58}{15} + \frac{67}{10} = \frac{58 \cdot 2}{30} + \frac{67 \cdot 3}{30} = \frac{116 + 201}{30} = \frac{317}{30} = 10\frac{17}{30} \)
3. \( 9\frac{8}{21} + 4\frac{11}{14} = \frac{9 \cdot 21 + 8}{21} + \frac{4 \cdot 14 + 11}{14} = \frac{189 + 8}{21} + \frac{56 + 11}{14} = \frac{197}{21} + \frac{67}{14} = \frac{197 \cdot 2}{42} + \frac{67 \cdot 3}{42} = \frac{394 + 201}{42} = \frac{595}{42} = 14\frac{7}{42} = 14\frac{1}{6} \)
4. \( 8\frac{5}{9} + 7\frac{3}{4} + 12\frac{7}{12} = \frac{8 \cdot 9 + 5}{9} + \frac{7 \cdot 4 + 3}{4} + \frac{12 \cdot 12 + 7}{12} = \frac{77}{9} + \frac{31}{4} + \frac{151}{12} = \frac{77 \cdot 4}{36} + \frac{31 \cdot 9}{36} + \frac{151 \cdot 3}{36} = \frac{308 + 279 + 453}{36} = \frac{1040}{36} = \frac{260}{9} = 28\frac{8}{9} \)

Ответ: 1) \( 20\frac{7}{24} \); 2) \( 10\frac{17}{30} \); 3) \( 14\frac{1}{6} \); 4) \( 28\frac{8}{9} \).