Вариант 1. Задание 3: Вычислите: 1) 3/8 + 4/9; 2) 7/12 - 3/8; 3) 2 5/8 + 1 3/10; 4) 6 7/10 - 4 5/12

1) \(\frac{3}{8} + \frac{4}{9} = \frac{3 \cdot 9}{8 \cdot 9} + \frac{4 \cdot 8}{9 \cdot 8} = \frac{27}{72} + \frac{32}{72} = \frac{27 + 32}{72} = \frac{59}{72}\) 2) \(\frac{7}{12} - \frac{3}{8} = \frac{7 \cdot 2}{12 \cdot 2} - \frac{3 \cdot 3}{8 \cdot 3} = \frac{14}{24} - \frac{9}{24} = \frac{14 - 9}{24} = \frac{5}{24}\) 3) \(2 \frac{5}{8} + 1 \frac{3}{10} = 2 + \frac{5}{8} + 1 + \frac{3}{10} = 3 + \frac{5 \cdot 5}{8 \cdot 5} + \frac{3 \cdot 4}{10 \cdot 4} = 3 + \frac{25}{40} + \frac{12}{40} = 3 + \frac{37}{40} = 3 \frac{37}{40}\) 4) \(6 \frac{7}{10} - 4 \frac{5}{12} = 6 + \frac{7}{10} - 4 - \frac{5}{12} = 2 + \frac{7 \cdot 6}{10 \cdot 6} - \frac{5 \cdot 5}{12 \cdot 5} = 2 + \frac{42}{60} - \frac{25}{60} = 2 + \frac{17}{60} = 2 \frac{17}{60}\)