279. Вычислите:

Решение:

1. \( 1 - \frac{13}{55} = \frac{55}{55} - \frac{13}{55} = \frac{42}{55} \)
2. \( 6 - \frac{9}{20} = \frac{6 · 20}{20} - \frac{9}{20} = \frac{120}{20} - \frac{9}{20} = \frac{111}{20} = 5\frac{11}{20} \)
3. \( 10 - 5\frac{12}{35} = 10 - \frac{5 · 35 + 12}{35} = 10 - \frac{175+12}{35} = 10 - \frac{187}{35} = \frac{10 · 35}{35} - \frac{187}{35} = \frac{350}{35} - \frac{187}{35} = \frac{163}{35} = 4\frac{23}{35} \)
4. \( 8 - 4\frac{5}{22} = 8 - \frac{4 · 22 + 5}{22} = 8 - \frac{88+5}{22} = 8 - \frac{93}{22} = \frac{8 · 22}{22} - \frac{93}{22} = \frac{176}{22} - \frac{93}{22} = \frac{83}{22} = 3\frac{17}{22} \)

Ответ: 1) \( \frac{42}{55} \); 2) \( 5\frac{11}{20} \); 3) \( 4\frac{23}{35} \); 4) \( 3\frac{17}{22} \).