47. Вычислите: 1) 5/7 + 1/4; 2) 7/15 − 3/10; 3) 11/18 − 4/9; 4) 7/30 + 9/20; 5) 11/16 − 5/12; 6) 5/18 + 4/27; 7) 19/42 − 3/28; 8) 8/9 − 5/6 + 1/3; 9) 9/16 + 5/6 − 7/24.

1. \(\frac{5}{7}+\frac{1}{4}=\frac{20}{28}+\frac{7}{28}=\frac{27}{28}\).
2. \(\frac{7}{15}-\frac{3}{10}=\frac{14}{30}-\frac{9}{30}=\frac{5}{30}=\frac{1}{6}\).
3. \(\frac{11}{18}-\frac{4}{9}=\frac{11}{18}-\frac{8}{18}=\frac{3}{18}=\frac{1}{6}\).
4. \(\frac{7}{30}+\frac{9}{20}=\frac{14}{60}+\frac{27}{60}=\frac{41}{60}\).
5. \(\frac{11}{16}-\frac{5}{12}=\frac{33}{48}-\frac{20}{48}=\frac{13}{48}\).
6. \(\frac{5}{18}+\frac{4}{27}=\frac{15}{54}+\frac{8}{54}=\frac{23}{54}\).
7. \(\frac{19}{42}-\frac{3}{28}=\frac{38}{84}-\frac{9}{84}=\frac{29}{84}\).
8. \(\frac{8}{9}-\frac{5}{6}+\frac{1}{3}=\frac{16}{18}-\frac{15}{18}+\frac{6}{18}=\frac{7}{18}\).
9. \(\frac{9}{16}+\frac{5}{6}-\frac{7}{24}=\frac{27}{48}+\frac{40}{48}-\frac{14}{48}=\frac{53}{48}=1\frac{5}{48}\).

Ответ: 1) \(\frac{27}{28}\); 2) \(\frac{1}{6}\); 3) \(\frac{1}{6}\); 4) \(\frac{41}{60}\); 5) \(\frac{13}{48}\); 6) \(\frac{23}{54}\); 7) \(\frac{29}{84}\); 8) \(\frac{7}{18}\); 9) \(1\frac{5}{48}\).