1. Вычислите: A) \frac{2}{3} + \frac{1}{9}; Б) \frac{3}{4} : 1\frac{1}{8}; В) 3 - \frac{2}{3} \cdot \frac{3}{7}

А) \frac{2}{3} + \frac{1}{9} \frac{2}{3} + \frac{1}{9} = \frac{2 \cdot 3}{3 \cdot 3} + \frac{1}{9} = \frac{6}{9} + \frac{1}{9} = \frac{6 + 1}{9} = \frac{7}{9} Ответ: \frac{7}{9} Б) \frac{3}{4} : 1\frac{1}{8} \frac{3}{4} : 1\frac{1}{8} = \frac{3}{4} : \frac{9}{8} = \frac{3}{4} \cdot \frac{8}{9} = \frac{3 \cdot 8}{4 \cdot 9} = \frac{24}{36} = \frac{2}{3} Ответ: \frac{2}{3} В) 3 - \frac{2}{3} \cdot \frac{3}{7} 3 - \frac{2}{3} \cdot \frac{3}{7} = 3 - \frac{2 \cdot 3}{3 \cdot 7} = 3 - \frac{6}{21} = 3 - \frac{2}{7} = \frac{3 \cdot 7}{7} - \frac{2}{7} = \frac{21}{7} - \frac{2}{7} = \frac{21 - 2}{7} = \frac{19}{7} = 2\frac{5}{7} Ответ: 2\frac{5}{7}