(9 - 2 2/3 : 2 1/7) * 21/46

Привет! Давай решим примеры по порядку. **1.** $\left(9 - 2\frac{2}{3} : 2\frac{1}{7}\right) \cdot \frac{21}{46} = \left(9 - \frac{8}{3} : \frac{15}{7}\right) \cdot \frac{21}{46} = \left(9 - \frac{8}{3} \cdot \frac{7}{15}\right) \cdot \frac{21}{46} = \left(9 - \frac{56}{45}\right) \cdot \frac{21}{46} = \frac{405 - 56}{45} \cdot \frac{21}{46} = \frac{349}{45} \cdot \frac{21}{46} = \frac{349 \cdot 7}{15 \cdot 46} = \frac{2443}{690} = 3\frac{373}{690}$ **2.** $\frac{27}{34} \cdot \left(5 - 2\frac{4}{5} \cdot 1\frac{1}{9}\right) = \frac{27}{34} \cdot \left(5 - \frac{14}{5} \cdot \frac{10}{9}\right) = \frac{27}{34} \cdot \left(5 - \frac{28}{9}\right) = \frac{27}{34} \cdot \left(\frac{45-28}{9}\right) = \frac{27}{34} \cdot \frac{17}{9} = \frac{3}{2} = 1,5$ **3.** $\left(9 - 2\frac{2}{15} \cdot 3\frac{1}{8}\right) \cdot \frac{9}{14} = \left(9 - \frac{32}{15} \cdot \frac{25}{8}\right) \cdot \frac{9}{14} = \left(9 - \frac{4 \cdot 5}{3 \cdot 1}\right) \cdot \frac{9}{14} = \left(9 - \frac{20}{3}\right) \cdot \frac{9}{14} = \frac{7}{3} \cdot \frac{9}{14} = \frac{3}{2} = 1,5$ **4.** $\frac{6}{29} \cdot \left(6 - 2\frac{3}{11} \cdot 1\frac{2}{9}\right) = \frac{6}{29} \cdot \left(6 - \frac{25}{11} \cdot \frac{11}{9}\right) = \frac{6}{29} \cdot \left(6 - \frac{25}{9}\right) = \frac{6}{29} \cdot \left(\frac{54-25}{9}\right) = \frac{6}{29} \cdot \frac{29}{9} = \frac{2}{3}$ **5.** $5\frac{2}{3} : \frac{1}{3} - 1\frac{7}{12} \cdot 6 = \frac{17}{3} \cdot 3 - \frac{19}{12} \cdot 6 = 17 - \frac{19}{2} = 17 - 9,5 = 7,5$ **6.** $4\frac{3}{7} : \frac{1}{7} - 1\frac{5}{6} \cdot 3 = \frac{31}{7} \cdot 7 - \frac{11}{6} \cdot 3 = 31 - 5,5 = 25,5$ **7.** $3\frac{3}{8} : \frac{1}{8} - 1\frac{5}{14} \cdot 7 = \frac{27}{8} \cdot 8 - \frac{19}{14} \cdot 7 = 27 - 9,5 = 17,5$ **8.** а) $\frac{1}{6}x + \frac{5}{12}x = 8,4 \Rightarrow \frac{2}{12}x + \frac{5}{12}x = 8,4 \Rightarrow \frac{7}{12}x = 8,4 \Rightarrow x = 8,4 : \frac{7}{12} = 8,4 \cdot \frac{12}{7} = 1,2 \cdot 12 = 14,4$ б) $\frac{1}{7}x + \frac{3}{14}x = 14 \Rightarrow \frac{2}{14}x + \frac{3}{14}x = 14 \Rightarrow \frac{5}{14}x = 14 \Rightarrow x = 14 : \frac{5}{14} = 14 \cdot \frac{14}{5} = \frac{196}{5} = 39,2$ в) $3,85x + 2,15x = 7,2 \Rightarrow 6x = 7,2 \Rightarrow x = 1,2$ г) $4,6y + 3,8y = 2,1 \Rightarrow 8,4y = 2,1 \Rightarrow y = 2,1 : 8,4 = 0,25$