Реши примеры с дробями из задания 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 64

31. $\frac{12}{25} \cdot \frac{5}{16} = \frac{12 \cdot 5}{25 \cdot 16} = \frac{3 \cdot 1}{5 \cdot 4} = \frac{3}{20}$ 33. $2 \frac{2}{3} \cdot 3 \frac{3}{4} = \frac{8}{3} \cdot \frac{15}{4} = \frac{8 \cdot 15}{3 \cdot 4} = \frac{2 \cdot 5}{1 \cdot 1} = 10$ 35. $0 \cdot 12 \frac{5}{8} = 0$ 37. $(\frac{5}{12} + \frac{3}{8}) \cdot \frac{6}{19} = (\frac{10}{24} + \frac{9}{24}) \cdot \frac{6}{19} = \frac{19}{24} \cdot \frac{6}{19} = \frac{1}{4}$ 39. $\frac{2}{3} \cdot \frac{9}{16} - \frac{7}{24} \cdot \frac{2}{7} = \frac{2 \cdot 9}{3 \cdot 16} - \frac{7 \cdot 2}{24 \cdot 7} = \frac{3}{8} - \frac{1}{12} = \frac{9}{24} - \frac{2}{24} = \frac{7}{24}$ 41. $8 \frac{3}{5} - \frac{3}{5} \cdot \frac{15}{27} = \frac{43}{5} - \frac{3 \cdot 15}{5 \cdot 27} = \frac{43}{5} - \frac{1 \cdot 5}{5 \cdot 3} = \frac{43}{5} - \frac{1}{3} = \frac{129}{15} - \frac{5}{15} = \frac{124}{15} = 8 \frac{4}{15}$ 43. $\frac{4}{5} : \frac{8}{25} = \frac{4}{5} \cdot \frac{25}{8} = \frac{4 \cdot 25}{5 \cdot 8} = \frac{1 \cdot 5}{1 \cdot 2} = \frac{5}{2} = 2 \frac{1}{2}$ 45. $1 : \frac{3}{17} = 1 \cdot \frac{17}{3} = \frac{17}{3} = 5 \frac{2}{3}$ 47. $0 \cdot 5,6 = 0$ 49. $3 \frac{7}{12} : 1 = 3 \frac{7}{12}$ 51. $2 \frac{2}{3} : 1 \frac{1}{31} = \frac{8}{3} : \frac{32}{31} = \frac{8}{3} \cdot \frac{31}{32} = \frac{1 \cdot 31}{3 \cdot 4} = \frac{31}{12} = 2 \frac{7}{12}$ 53. $\frac{11}{12} \cdot \frac{7}{12} \cdot \frac{21}{55} = \frac{11 \cdot 7 \cdot 21}{12 \cdot 12 \cdot 55} = \frac{1 \cdot 7 \cdot 7}{4 \cdot 12 \cdot 5} = \frac{49}{240}$ 55. $\frac{15}{16} : \frac{3}{8} \cdot \frac{2}{5} = \frac{15}{16} \cdot \frac{8}{3} \cdot \frac{2}{5} = \frac{15 \cdot 8 \cdot 2}{16 \cdot 3 \cdot 5} = \frac{1 \cdot 1 \cdot 1}{1 \cdot 1 \cdot 1} = 1$ 57. $(3 \frac{1}{6} - 2 \frac{7}{15}) : 1 \frac{2}{5} = (\frac{19}{6} - \frac{37}{15}) : \frac{7}{5} = (\frac{95}{30} - \frac{74}{30}) : \frac{7}{5} = \frac{21}{30} : \frac{7}{5} = \frac{7}{10} \cdot \frac{5}{7} = \frac{1}{2}$ 59. $-2 \frac{1}{2} - 1 \frac{2}{3} = -\frac{5}{2} - \frac{5}{3} = -\frac{15}{6} - \frac{10}{6} = -\frac{25}{6} = -4 \frac{1}{6}$ 61. $3 \frac{1}{4} - (-5) = \frac{13}{4} + 5 = \frac{13}{4} + \frac{20}{4} = \frac{33}{4} = 8 \frac{1}{4}$ 63. $-\frac{3}{8} \cdot (-\frac{1}{9}) = \frac{3 \cdot 1}{8 \cdot 9} = \frac{1}{24}$ 64. $-\frac{2}{7} : (-\frac{8}{21}) = -\frac{2}{7} \cdot (-\frac{21}{8}) = \frac{2 \cdot 21}{7 \cdot 8} = \frac{1 \cdot 3}{1 \cdot 4} = \frac{3}{4}$