311.1) 5/6 * 8; 23/20 * 10; 23/40 * 8; 11/12 * 6; 8/15 * 3; 9/35 * 7; 8/9 : 4; 3/4 : 6; 2/7 : 2; 8/15 : 4; 2/5 : 3; 6/7 : 6; 2) 9/16 * 8; 11/14 * 2; 23/24 * 6; 3/20 * 10; 17/30 * 6; 13/18 * 6; 12/13 : 4; 4/9 : 14; 3/4 : 2; 5/6 : 10; 4/5 : 8; 14/15 : 12.

Решение:

Выполним вычисления для каждого примера:

1. 311.1)
   • \[ \frac{5}{6} \times 8 = \frac{5 \times 8}{6} = \frac{40}{6} = \frac{20}{3} \]
   • \[ \frac{23}{20} \times 10 = \frac{23 \times 10}{20} = \frac{230}{20} = \frac{23}{2} \]
   • \[ \frac{23}{40} \times 8 = \frac{23 \times 8}{40} = \frac{184}{40} = \frac{23}{5} \]
   • \[ \frac{11}{12} \times 6 = \frac{11 \times 6}{12} = \frac{66}{12} = \frac{11}{2} \]
   • \[ \frac{8}{15} \times 3 = \frac{8 \times 3}{15} = \frac{24}{15} = \frac{8}{5} \]
   • \[ \frac{9}{35} \times 7 = \frac{9 \times 7}{35} = \frac{63}{35} = \frac{9}{5} \]
   • \[ \frac{8}{9} : 4 = \frac{8}{9 \times 4} = \frac{8}{36} = \frac{2}{9} \]
   • \[ \frac{3}{4} : 6 = \frac{3}{4 \times 6} = \frac{3}{24} = \frac{1}{8} \]
   • \[ \frac{2}{7} : 2 = \frac{2}{7 \times 2} = \frac{2}{14} = \frac{1}{7} \]
   • \[ \frac{8}{15} : 4 = \frac{8}{15 \times 4} = \frac{8}{60} = \frac{2}{15} \]
   • \[ \frac{2}{5} : 3 = \frac{2}{5 \times 3} = \frac{2}{15} \]
   • \[ \frac{6}{7} : 6 = \frac{6}{7 \times 6} = \frac{6}{42} = \frac{1}{7} \]
2. 2)
   • \[ \frac{9}{16} \times 8 = \frac{9 \times 8}{16} = \frac{72}{16} = \frac{9}{2} \]
   • \[ \frac{11}{14} \times 2 = \frac{11 \times 2}{14} = \frac{22}{14} = \frac{11}{7} \]
   • \[ \frac{23}{24} \times 6 = \frac{23 \times 6}{24} = \frac{138}{24} = \frac{23}{4} \]
   • \[ \frac{3}{20} \times 10 = \frac{3 \times 10}{20} = \frac{30}{20} = \frac{3}{2} \]
   • \[ \frac{17}{30} \times 6 = \frac{17 \times 6}{30} = \frac{102}{30} = \frac{17}{5} \]
   • \[ \frac{13}{18} \times 6 = \frac{13 \times 6}{18} = \frac{78}{18} = \frac{13}{3} \]
   • \[ \frac{12}{13} : 4 = \frac{12}{13 \times 4} = \frac{12}{52} = \frac{3}{13} \]
   • \[ \frac{4}{9} : 14 = \frac{4}{9 \times 14} = \frac{4}{126} = \frac{2}{63} \]
   • \[ \frac{3}{4} : 2 = \frac{3}{4 \times 2} = \frac{3}{8} \]
   • \[ \frac{5}{6} : 10 = \frac{5}{6 \times 10} = \frac{5}{60} = \frac{1}{12} \]
   • \[ \frac{4}{5} : 8 = \frac{4}{5 \times 8} = \frac{4}{40} = \frac{1}{10} \]
   • \[ \frac{14}{15} : 12 = \frac{14}{15 \times 12} = \frac{14}{180} = \frac{7}{90} \]