Вычислите: 8/35 * (5/6 + 11/12)

**11. Ответ: $$\frac{1}{2}$$** 1) $$\frac{5}{6} + \frac{11}{12} = \frac{10}{12} + \frac{11}{12} = \frac{21}{12} = \frac{7}{4}$$ 2) $$\frac{8}{35} \cdot \frac{7}{4} = \frac{8 \cdot 7}{35 \cdot 4} = \frac{2 \cdot 1}{5 \cdot 1} = \frac{2}{5} = 0,4$$ (или $$\frac{2}{5}$$) **12. Ответ: $$\frac{1}{12}$$** 1) $$\frac{5}{6} - \frac{7}{18} = \frac{15}{18} - \frac{7}{18} = \frac{8}{18} = \frac{4}{9}$$ 2) $$\frac{4}{9} \cdot \frac{3}{16} = \frac{4 \cdot 3}{9 \cdot 16} = \frac{1 \cdot 1}{3 \cdot 4} = \frac{1}{12}$$ **13. Ответ: $$\frac{2}{15}$$** 1) $$\frac{14}{25} : \frac{7}{45} = \frac{14}{25} \cdot \frac{45}{7} = \frac{14 \cdot 45}{25 \cdot 7} = \frac{2 \cdot 9}{5 \cdot 1} = \frac{18}{5}$$ 2) $$\frac{18}{5} - 3 = \frac{18}{5} - \frac{15}{5} = \frac{3}{5} = 0,6$$ (или $$\frac{3}{5}$$) **14. Ответ: $$\frac{4}{5}$$** 1) $$\frac{15}{28} : \frac{10}{21} = \frac{15}{28} \cdot \frac{21}{10} = \frac{15 \cdot 21}{28 \cdot 10} = \frac{3 \cdot 3}{4 \cdot 2} = \frac{9}{8}$$ 2) $$2 - \frac{9}{8} = \frac{16}{8} - \frac{9}{8} = \frac{7}{8} = 0,875$$ (или $$\frac{7}{8}$$) **15. Ответ: $$\frac{1}{4}$$** 1) $$\frac{21}{26} : \frac{14}{39} = \frac{21}{26} \cdot \frac{39}{14} = \frac{21 \cdot 39}{26 \cdot 14} = \frac{3 \cdot 3}{2 \cdot 2} = \frac{9}{4}$$ 2) $$\frac{9}{4} - 2 = \frac{9}{4} - \frac{8}{4} = \frac{1}{4} = 0,25$$ (или $$\frac{1}{4}$$) **16. Ответ: $$\frac{49}{64}$$** 1) $$1 - \frac{4}{7} = \frac{7}{7} - \frac{4}{7} = \frac{3}{7}$$ 2) $$\frac{3}{7} : \frac{16}{21} = \frac{3}{7} \cdot \frac{21}{16} = \frac{3 \cdot 21}{7 \cdot 16} = \frac{3 \cdot 3}{1 \cdot 16} = \frac{9}{16}$$