Решение:
- \( 14 - 13,2 : \left( 3\frac{11}{21} - 2\frac{1}{5} \right) \)
- \( 3\frac{11}{21} - 2\frac{1}{5} = \frac{74}{21} - \frac{11}{5} = \frac{74 \cdot 5 - 11 \cdot 21}{105} = \frac{370 - 231}{105} = \frac{139}{105} \)
- \( 14 - 13,2 : \frac{139}{105} = 14 - \frac{132}{10} \cdot \frac{105}{139} = 14 - \frac{66}{5} \cdot \frac{105}{139} = 14 - \frac{66 \cdot 21}{139} = 14 - \frac{1386}{139} = \frac{14 \cdot 139 - 1386}{139} = \frac{1946 - 1386}{139} = \frac{560}{139} \)
- \( \frac{5}{12}y + 1,3 = 0,53 + \frac{7}{8}y \)
- \( \frac{5}{12}y - \frac{7}{8}y = 0,53 - 1,3 \)
- \( \frac{10y - 21y}{24} = -0,77 \)
- \( \frac{-11y}{24} = -0,77 \)
- \( y = \frac{-0,77 \cdot 24}{-11} = 0,07 \cdot 24 = 1,68 \)
- \( 7,6 : x = 2\frac{6}{7} : 2\frac{4}{9} \)
- \( 2\frac{6}{7} = \frac{20}{7} \)
- \( 2\frac{4}{9} = \frac{22}{9} \)
- \( \frac{20}{7} : \frac{22}{9} = \frac{20}{7} \cdot \frac{9}{22} = \frac{10}{7} \cdot \frac{9}{11} = \frac{90}{77} \)
- \( 7,6 : x = \frac{90}{77} \)
- \( x = 7,6 : \frac{90}{77} = \frac{76}{10} \cdot \frac{77}{90} = \frac{38}{5} \cdot \frac{77}{90} = \frac{19}{5} \cdot \frac{77}{45} = \frac{1463}{225} \)
- \( -0,24 : \left( 2\frac{5}{6} : 2,15 - 1,5093 \right) : 1,1 \)
- \( 2\frac{5}{6} = \frac{17}{6} \)
- \( \frac{17}{6} : 2,15 = \frac{17}{6} : \frac{215}{100} = \frac{17}{6} \cdot \frac{100}{215} = \frac{17}{3} \cdot \frac{50}{215} = \frac{17 \cdot 50}{3 \cdot 215} = \frac{850}{645} = \frac{170}{129} \approx 1,3178 \)
- \( 1,3178 - 1,5093 = -0,1915 \)
- \( -0,24 : (-0,1915) : 1,1 \approx 1,253 : 1,1 \approx 1,139 \)
Ответ:
1. \( \frac{560}{139} \)
2. \( y = 1,68 \)
3. \( x = \frac{1463}{225} \)
4. \( \approx 1,139 \)