778. Вычислите: 8) 10-93 10 9) 5륵-2; 7 6 10) 1420-812; 9 11) 814-514 16 12)71-4 21' 8 68 631 13) 14 31 5 15 14) (12+7)-(132-9).

Ответ:

1. 10 - 9 \(\frac{3}{10}\) = 9 \(\frac{10}{10}\) - 9 \(\frac{3}{10}\) = (9 - 9) + (\(\frac{10}{10}\) - \(\frac{3}{10}\)) = 0 + \(\frac{7}{10}\) = \(\frac{7}{10}\)
2. 5 \(\frac{2}{7}\) - 2 \(\frac{5}{7}\) = 4 \(\frac{9}{7}\) - 2 \(\frac{5}{7}\) = (4 - 2) + (\(\frac{9}{7}\) - \(\frac{5}{7}\)) = 2 + \(\frac{4}{7}\) = 2 \(\frac{4}{7}\)
3. 14 \(\frac{6}{20}\) - 8 \(\frac{12}{20}\) = 13 \(\frac{26}{20}\) - 8 \(\frac{12}{20}\) = (13 - 8) + (\(\frac{26}{20}\) - \(\frac{12}{20}\)) = 5 + \(\frac{14}{20}\) = 5 \(\frac{7}{10}\)
4. 8 \(\frac{3}{14}\) - 5 \(\frac{9}{14}\) = 7 \(\frac{17}{14}\) - 5 \(\frac{9}{14}\) = (7 - 5) + (\(\frac{17}{14}\) - \(\frac{9}{14}\)) = 2 + \(\frac{8}{14}\) = 2 \(\frac{4}{7}\)
5. 7 \(\frac{10}{21}\) - 4 \(\frac{16}{21}\) = 6 \(\frac{31}{21}\) - 4 \(\frac{16}{21}\) = (6 - 4) + (\(\frac{31}{21}\) - \(\frac{16}{21}\)) = 2 + \(\frac{15}{21}\) = 2 \(\frac{5}{7}\)
6. 14 \(\frac{8}{31}\) - 6 \(\frac{8}{31}\) = (14 - 6) + (\(\frac{8}{31}\) - \(\frac{8}{31}\)) = 8 + 0 = 8
7. (12 \(\frac{5}{22}\) + 7 \(\frac{17}{22}\)) - (13 \(\frac{7}{23}\) - 9 \(\frac{15}{23}\)) = (12 + 7) + (\(\frac{5}{22}\) + \(\frac{17}{22}\)) - ((13 - 9) + (\(\frac{7}{23}\) - \(\frac{15}{23}\))) = 19 + \(\frac{22}{22}\) - (4 - \(\frac{8}{23}\)) = 19 + 1 - 4 + \(\frac{8}{23}\) = 16 + \(\frac{8}{23}\) = 16 \(\frac{8}{23}\)

Ответ:

8) \(\frac{7}{10}\)

9) 2 \(\frac{4}{7}\)

10) 5 \(\frac{7}{10}\)

11) 2 \(\frac{4}{7}\)

12) 2 \(\frac{5}{7}\)

13) 8

14) 16 \(\frac{8}{23}\)