Решаю все задания по порядку:
1. Выполняю сложение.
a) $\frac{4}{9} + \frac{3}{5} = \frac{4 \cdot 5 + 3 \cdot 9}{9 \cdot 5} = \frac{20 + 27}{45} = \frac{47}{45} = 1\frac{2}{45}$
б) $\frac{7}{18} + \frac{7}{12} = \frac{7 \cdot 2 + 7 \cdot 3}{36} = \frac{14 + 21}{36} = \frac{35}{36}$
в) $\frac{11}{25} + \frac{13}{30} = \frac{11 \cdot 6 + 13 \cdot 5}{150} = \frac{66 + 65}{150} = \frac{131}{150}$
г) $\frac{5}{38} + \frac{7}{19} = \frac{5 + 7 \cdot 2}{38} = \frac{5 + 14}{38} = \frac{19}{38} = \frac{1}{2}$
2. Выполняю вычитание.
a) $\frac{1}{11} - \frac{1}{33} = \frac{3 - 1}{33} = \frac{2}{33}$
б) $\frac{7}{11} - \frac{5}{8} = \frac{7 \cdot 8 - 5 \cdot 11}{88} = \frac{56 - 55}{88} = \frac{1}{88}$
в) $\frac{13}{30} - \frac{2}{45} = \frac{13 \cdot 3 - 2 \cdot 2}{90} = \frac{39 - 4}{90} = \frac{35}{90} = \frac{7}{18}$
г) $\frac{13}{60} - \frac{7}{40} = \frac{13 \cdot 2 - 7 \cdot 3}{120} = \frac{26 - 21}{120} = \frac{5}{120} = \frac{1}{24}$
3. Выполняю действия.
a) $4\frac{1}{6} + 3\frac{2}{5} = \frac{25}{6} + \frac{17}{5} = \frac{25 \cdot 5 + 17 \cdot 6}{30} = \frac{125 + 102}{30} = \frac{227}{30} = 7\frac{17}{30}$
б) $8\frac{3}{4} - 7\frac{5}{6} = \frac{35}{4} - \frac{47}{6} = \frac{35 \cdot 3 - 47 \cdot 2}{12} = \frac{105 - 94}{12} = \frac{11}{12}$
в) $2\frac{11}{12} + 6\frac{5}{8} = \frac{35}{12} + \frac{53}{8} = \frac{35 \cdot 2 + 53 \cdot 3}{24} = \frac{70 + 159}{24} = \frac{229}{24} = 9\frac{13}{24}$
г) $2\frac{13}{14} - 1\frac{20}{21} = \frac{41}{14} - \frac{41}{21} = 41 \cdot (\frac{1}{14} - \frac{1}{21}) = 41 \cdot \frac{3 - 2}{42} = 41 \cdot \frac{1}{42} = \frac{41}{42}$
4. Выполняю умножение.
a) $\frac{3}{8} \cdot \frac{9}{11} = \frac{3 \cdot 9}{8 \cdot 11} = \frac{27}{88}$
б) $\frac{22}{35} \cdot \frac{21}{44} = \frac{11 \cdot 2 \cdot 7 \cdot 3}{7 \cdot 5 \cdot 11 \cdot 4} = \frac{2 \cdot 3}{5 \cdot 4} = \frac{6}{20} = \frac{3}{10}$
в) $5\frac{3}{5} \cdot 1\frac{4}{21} = \frac{28}{5} \cdot \frac{25}{21} = \frac{4 \cdot 7 \cdot 5 \cdot 5}{5 \cdot 7 \cdot 3} = \frac{4 \cdot 5}{3} = \frac{20}{3} = 6\frac{2}{3}$
г) $9\frac{3}{7} \cdot 1\frac{3}{11} = \frac{66}{7} \cdot \frac{14}{11} = \frac{6 \cdot 11 \cdot 2 \cdot 7}{7 \cdot 11} = 6 \cdot 2 = 12$
д) $1\frac{1}{15} \cdot \frac{5}{16} = \frac{16}{15} \cdot \frac{5}{16} = \frac{16 \cdot 5}{3 \cdot 5 \cdot 16} = \frac{1}{3}$
e) $\frac{7}{11} \cdot 2\frac{5}{14} = \frac{7}{11} \cdot \frac{33}{14} = \frac{7 \cdot 3 \cdot 11}{11 \cdot 2 \cdot 7} = \frac{3}{2} = 1\frac{1}{2}$
5. Выполняю деление.
a) $\frac{6}{25} : \frac{9}{5} = \frac{6}{25} \cdot \frac{5}{9} = \frac{2 \cdot 3 \cdot 5}{5 \cdot 5 \cdot 3 \cdot 3} = \frac{2}{5 \cdot 3} = \frac{2}{15}$
б) $\frac{8}{27} : \frac{8}{9} = \frac{8}{27} \cdot \frac{9}{8} = \frac{8 \cdot 9}{3 \cdot 9 \cdot 8} = \frac{1}{3}$
в) $6\frac{2}{3} : 1\frac{1}{8} = \frac{20}{3} : \frac{9}{8} = \frac{20}{3} \cdot \frac{8}{9} = \frac{20 \cdot 8}{3 \cdot 9} = \frac{160}{27} = 5\frac{25}{27}$
г) $\frac{36}{47} : 18 = \frac{36}{47} \cdot \frac{1}{18} = \frac{2 \cdot 18}{47 \cdot 18} = \frac{2}{47}$
д) $9\frac{5}{7} : 1\frac{23}{28} = \frac{68}{7} : \frac{51}{28} = \frac{68}{7} \cdot \frac{28}{51} = \frac{4 \cdot 17 \cdot 4 \cdot 7}{7 \cdot 3 \cdot 17} = \frac{4 \cdot 4}{3} = \frac{16}{3} = 5\frac{1}{3}$
e) $42 : \frac{6}{7} = 42 \cdot \frac{7}{6} = 7 \cdot 6 \cdot \frac{7}{6} = 7 \cdot 7 = 49$
ж) $-6\frac{2}{3} : \frac{8}{9} = -\frac{20}{3} : \frac{8}{9} = -\frac{20}{3} \cdot \frac{9}{8} = -\frac{5 \cdot 4 \cdot 3 \cdot 3}{3 \cdot 2 \cdot 4} = -\frac{5 \cdot 3}{2} = -\frac{15}{2} = -7\frac{1}{2}$
з) $-\frac{36}{47} : (-9) = \frac{36}{47} : 9 = \frac{36}{47} \cdot \frac{1}{9} = \frac{4 \cdot 9}{47 \cdot 9} = \frac{4}{47}$
6. Решаю уравнения.
a) $\frac{8}{21} : m = \frac{2}{3}$
Чтобы найти неизвестный делитель, нужно делимое разделить на частное:
$m = \frac{8}{21} : \frac{2}{3} = \frac{8}{21} \cdot \frac{3}{2} = \frac{4 \cdot 2 \cdot 3}{7 \cdot 3 \cdot 2} = \frac{4}{7}$
б) $1\frac{5}{7}x - \frac{5}{9} = 2\frac{4}{9}$
Сначала перенесем $-\frac{5}{9}$ в правую часть уравнения, изменив знак на плюс:
$1\frac{5}{7}x = 2\frac{4}{9} + \frac{5}{9}$
$1\frac{5}{7}x = 2\frac{9}{9} = 3$
Теперь выразим $x$:
$x = 3 : 1\frac{5}{7} = 3 : \frac{12}{7} = 3 \cdot \frac{7}{12} = \frac{3 \cdot 7}{3 \cdot 4} = \frac{7}{4} = 1\frac{3}{4}$
в) $\frac{5}{14}n - \frac{1}{3}n + \frac{1}{7}n = \frac{1}{4}$
Приведем дроби к общему знаменателю:
$\frac{15}{42}n - \frac{14}{42}n + \frac{6}{42}n = \frac{1}{4}$
$\frac{15 - 14 + 6}{42}n = \frac{1}{4}$
$\frac{7}{42}n = \frac{1}{4}$
$\frac{1}{6}n = \frac{1}{4}$
$n = \frac{1}{4} : \frac{1}{6} = \frac{1}{4} \cdot 6 = \frac{6}{4} = \frac{3}{2} = 1\frac{1}{2}$
7. Вычисляю:
a) $\frac{2\frac{4}{33} - 1\frac{7}{22} - \frac{1}{6}}{\frac{2}{3} + \frac{3}{4} - \frac{5}{6}} = \frac{\frac{66+4}{33} - \frac{22+7}{22} - \frac{1}{6}}{\frac{2 \cdot 4 + 3 \cdot 3 - 5 \cdot 2}{12}} = \frac{\frac{70}{33} - \frac{29}{22} - \frac{1}{6}}{\frac{8 + 9 - 10}{12}} = \frac{\frac{70 \cdot 4 - 29 \cdot 6 - 1 \cdot 22}{132}}{\frac{7}{12}} = \frac{\frac{280 - 174 - 22}{132}}{\frac{7}{12}} = \frac{\frac{84}{132}}{\frac{7}{12}} = \frac{84}{132} \cdot \frac{12}{7} = \frac{12 \cdot 7}{11 \cdot 12} \cdot \frac{12}{7} = \frac{12}{11} = 1\frac{1}{11}$
б) $\frac{-4 \cdot 1\frac{3}{4} : (-3\frac{1}{3})}{2,88 : (-4,8)} = \frac{-4 \cdot \frac{7}{4} : (-\frac{10}{3})}{-\frac{2,88}{4,8}} = \frac{-7 : (-\frac{10}{3})}{-\frac{288}{480}} = \frac{7 \cdot \frac{3}{10}}{\frac{3 \cdot 96}{5 \cdot 96}} = \frac{\frac{21}{10}}{\frac{3}{5}} = \frac{21}{10} \cdot \frac{5}{3} = \frac{7 \cdot 3 \cdot 5}{2 \cdot 5 \cdot 3} = \frac{7}{2} = 3\frac{1}{2}$