Карточка №10 Найдите значение выражения

1. $\frac{1}{10} - \frac{23}{20} = \frac{2}{20} - \frac{23}{20} = -\frac{21}{20} = -1,05$ 2. $\frac{5}{2} + \frac{1}{5} = \frac{25}{10} + \frac{2}{10} = \frac{27}{10} = 2,7$ 3. $\frac{8}{5 \cdot 4} = \frac{8}{20} = 0,4$ 4. $\frac{1}{1 + \frac{1}{4}} = \frac{1}{\frac{5}{4}} = \frac{4}{5} = 0,8$ 5. $\frac{1}{\frac{1}{36} + \frac{1}{45}} = \frac{1}{\frac{5 + 4}{180}} = \frac{1}{\frac{9}{180}} = \frac{1}{\frac{1}{20}} = 20$ 6. $(\frac{8}{33} + \frac{13}{22}) : \frac{5}{18} = (\frac{16 + 39}{66}) \cdot \frac{18}{5} = \frac{55}{66} \cdot \frac{18}{5} = \frac{5}{6} \cdot \frac{18}{5} = 3$ 7. $(2\frac{1}{16} - 1\frac{1}{14}) \cdot 28 = (\frac{33}{16} - \frac{15}{14}) \cdot 28 = \frac{33 \cdot 28}{16} - \frac{15 \cdot 28}{14} = \frac{33 \cdot 7}{4} - 30 = \frac{231}{4} - 30 = 57,75 - 30 = 27,75$ 8. 4\frac{3}{4} : (1\frac{1}{15} + \frac{3}{5}) = \frac{19}{4} : (\frac{16 + 9}{15}) = \frac{19}{4} : \frac{25}{15} = \frac{19}{4} : \frac{5}{3} = \frac{19}{4} \cdot \frac{3}{5} = \frac{57}{20} = 2,85$ 9. 9 \cdot (\frac{1}{9})^2 - 19 \cdot \frac{1}{9} = 9 \cdot \frac{1}{81} - \frac{19}{9} = \frac{1}{9} - \frac{19}{9} = -\frac{18}{9} = -2$ 10. (\frac{19}{25} - \frac{7}{13}) \cdot \frac{13}{12} = \frac{19 \cdot 13 - 7 \cdot 25}{25 \cdot 13} \cdot \frac{13}{12} = \frac{247 - 175}{25 \cdot 13} \cdot \frac{13}{12} = \frac{72}{25 \cdot 12} = \frac{6}{25} = 0,24