Вычислите: Найдите значение выражения 18 * (1/9)^2 - 20 * 1/9 и другие примеры с дробями.

1. $18 \cdot \left(\frac{1}{9}\right)^2 - 20 \cdot \frac{1}{9} = 18 \cdot \frac{1}{81} - \frac{20}{9} = \frac{18}{81} - \frac{20}{9} = \frac{2}{9} - \frac{20}{9} = -\frac{18}{9} = -2$ 2. $\frac{4}{25} + \frac{15}{4} = \frac{4 \cdot 4 + 15 \cdot 25}{100} = \frac{16 + 375}{100} = \frac{391}{100} = 3,91$ 3. $\frac{3}{2} - \frac{9}{5} = \frac{15 - 18}{10} = -\frac{3}{10} = -0,3$ 4. $\left(\frac{19}{8} + \frac{11}{12}\right) : \frac{5}{48} = \left(\frac{57 + 22}{24}\right) \cdot \frac{48}{5} = \frac{79}{24} \cdot \frac{48}{5} = \frac{79 \cdot 2}{5} = \frac{158}{5} = 31,6$ 5. $\frac{12}{20 \cdot 3} = \frac{12}{60} = \frac{1}{5} = 0,2$ 6. $\left(\frac{14}{11} + \frac{17}{10}\right) \cdot \frac{11}{15} = \frac{140 + 187}{110} \cdot \frac{11}{15} = \frac{327}{110} \cdot \frac{11}{15} = \frac{327}{10 \cdot 15} = \frac{109}{10 \cdot 5} = \frac{109}{50} = 2,18$ 7. $\left(2\frac{3}{4} + 2\frac{1}{5}\right) \cdot 16 = \left(\frac{11}{4} + \frac{11}{5}\right) \cdot 16 = \frac{55 + 44}{20} \cdot 16 = \frac{99}{20} \cdot 16 = \frac{99 \cdot 4}{5} = \frac{396}{5} = 79,2$ 8. $1\frac{8}{17} : \left(\frac{12}{17} + 2\frac{7}{11}\right) = \frac{25}{17} : \left(\frac{12}{17} + \frac{29}{11}\right) = \frac{25}{17} : \frac{132 + 493}{187} = \frac{25}{17} \cdot \frac{187}{625} = \frac{1 \cdot 11}{25} = \frac{11}{25} = 0,44$ 9. $\frac{1}{\frac{1}{18} - \frac{1}{21}} = \frac{1}{\frac{7 - 6}{126}} = \frac{1}{\frac{1}{126}} = 126$ 10. $\frac{9}{5} \cdot \frac{2}{3} = \frac{3 \cdot 2}{5} = \frac{6}{5} = 1,2$ Ответ: 1) -2; 2) 3,91; 3) -0,3; 4) 31,6; 5) 0,2; 6) 2,18; 7) 79,2; 8) 0,44; 9) 126; 10) 1,2.