Дом задание 7 +30 + 18 +휴⛤ 18 3)-4- 2 5)음+ 6)+ 27 38 1 7) - 8)-45 10 5 9)+麦加哥一最 11)-//=/ 12)x+=3+/4/ 5 13)-x=/

Решение:

1. $$\frac{4}{7} + \frac{5}{6} = \frac{4 \cdot 6}{7 \cdot 6} + \frac{5 \cdot 7}{6 \cdot 7} = \frac{24}{42} + \frac{35}{42} = \frac{24 + 35}{42} = \frac{59}{42} = 1 \frac{17}{42}$$
2. $$\frac{5}{18} + \frac{7}{30} = \frac{5 \cdot 5}{18 \cdot 5} + \frac{7 \cdot 3}{30 \cdot 3} = \frac{25}{90} + \frac{21}{90} = \frac{25 + 21}{90} = \frac{46}{90} = \frac{23}{45}$$
3. $$\frac{6}{7} - \frac{9}{14} = \frac{6 \cdot 2}{7 \cdot 2} - \frac{9}{14} = \frac{12}{14} - \frac{9}{14} = \frac{12 - 9}{14} = \frac{3}{14}$$
4. $$\frac{9}{20} - \frac{5}{12} = \frac{9 \cdot 3}{20 \cdot 3} - \frac{5 \cdot 5}{12 \cdot 5} = \frac{27}{60} - \frac{25}{60} = \frac{27 - 25}{60} = \frac{2}{60} = \frac{1}{30}$$
5. $$\frac{5}{12} + \frac{2}{15} = \frac{5 \cdot 5}{12 \cdot 5} + \frac{2 \cdot 4}{15 \cdot 4} = \frac{25}{60} + \frac{8}{60} = \frac{25 + 8}{60} = \frac{33}{60} = \frac{11}{20}$$
6. $$\frac{15}{19} + \frac{27}{38} = \frac{15 \cdot 2}{19 \cdot 2} + \frac{27}{38} = \frac{30}{38} + \frac{27}{38} = \frac{30 + 27}{38} = \frac{57}{38} = 1 \frac{19}{38} = 1 \frac{1}{2}$$
7. $$\frac{5}{9} - \frac{3}{8} = \frac{5 \cdot 8}{9 \cdot 8} - \frac{3 \cdot 9}{8 \cdot 9} = \frac{40}{72} - \frac{27}{72} = \frac{40 - 27}{72} = \frac{13}{72}$$
8. $$\frac{7}{18} - \frac{1}{45} = \frac{7 \cdot 5}{18 \cdot 5} - \frac{1 \cdot 2}{45 \cdot 2} = \frac{35}{90} - \frac{2}{90} = \frac{35 - 2}{90} = \frac{33}{90} = \frac{11}{30}$$
9. $$\frac{7}{15} + \frac{7}{12} = \frac{7 \cdot 4}{15 \cdot 4} + \frac{7 \cdot 5}{12 \cdot 5} = \frac{28}{60} + \frac{35}{60} = \frac{28 + 35}{60} = \frac{63}{60} = \frac{21}{20} = 1 \frac{1}{20}$$
10. $$\frac{7}{9} - \frac{5}{12} = \frac{7 \cdot 4}{9 \cdot 4} - \frac{5 \cdot 3}{12 \cdot 3} = \frac{28}{36} - \frac{15}{36} = \frac{28 - 15}{36} = \frac{13}{36}$$
11. $$x - \frac{3}{5} = \frac{1}{15}$$ $$x = \frac{1}{15} + \frac{3}{5}$$ $$x = \frac{1}{15} + \frac{3 \cdot 3}{5 \cdot 3}$$ $$x = \frac{1}{15} + \frac{9}{15}$$ $$x = \frac{1 + 9}{15}$$ $$x = \frac{10}{15} = \frac{2}{3}$$
12. $$x + \frac{1}{12} = \frac{1}{3} + \frac{1}{4}$$ $$x + \frac{1}{12} = \frac{1 \cdot 4}{3 \cdot 4} + \frac{1 \cdot 3}{4 \cdot 3}$$ $$x + \frac{1}{12} = \frac{4}{12} + \frac{3}{12}$$ $$x + \frac{1}{12} = \frac{4 + 3}{12}$$ $$x + \frac{1}{12} = \frac{7}{12}$$ $$x = \frac{7}{12} - \frac{1}{12}$$ $$x = \frac{7 - 1}{12}$$ $$x = \frac{6}{12} = \frac{1}{2}$$
13. $$\frac{9}{18} - x = \frac{5}{12}$$ $$\frac{1}{2} - x = \frac{5}{12}$$ $$x = \frac{1}{2} - \frac{5}{12}$$ $$x = \frac{1 \cdot 6}{2 \cdot 6} - \frac{5}{12}$$ $$x = \frac{6}{12} - \frac{5}{12}$$ $$x = \frac{6 - 5}{12}$$ $$x = \frac{1}{12}$$

Ответ: 1) $$1 \frac{17}{42}$$, 2) $$\frac{23}{45}$$, 3) $$\frac{3}{14}$$, 4) $$\frac{1}{30}$$, 5) $$\frac{11}{20}$$, 6) $$1 \frac{1}{2}$$, 7) $$\frac{13}{72}$$, 8) $$\frac{11}{30}$$, 9) $$1 \frac{1}{20}$$, 10) $$\frac{13}{36}$$, 11) $$\frac{2}{3}$$, 12) $$\frac{1}{2}$$, 13) $$\frac{1}{12}$$