4. Найдите значение выражения 1) \((\frac{1}{6} + \frac{1}{4}) \cdot 9\) 2) \((\frac{1}{5} + \frac{8}{15}) \cdot 6\) 3) \((\frac{3}{8} - \frac{1}{20}) \cdot 10\) 4) \((\frac{3}{4} - \frac{1}{6}) \cdot 3\)

1) \((\frac{1}{6} + \frac{1}{4}) \cdot 9 = (\frac{1 \cdot 2 + 1 \cdot 3}{12}) \cdot 9 = (\frac{2 + 3}{12}) \cdot 9 = \frac{5}{12} \cdot 9 = \frac{5 \cdot 9}{12} = \frac{5 \cdot 3 \cdot 3}{3 \cdot 4} = \frac{15}{4} = 3 \frac{3}{4}\) 2) \((\frac{1}{5} + \frac{8}{15}) \cdot 6 = (\frac{1 \cdot 3 + 8}{15}) \cdot 6 = (\frac{3 + 8}{15}) \cdot 6 = \frac{11}{15} \cdot 6 = \frac{11 \cdot 6}{15} = \frac{11 \cdot 2 \cdot 3}{5 \cdot 3} = \frac{22}{5} = 4 \frac{2}{5}\) 3) \((\frac{3}{8} - \frac{1}{20}) \cdot 10 = (\frac{3 \cdot 5 - 1 \cdot 2}{40}) \cdot 10 = (\frac{15 - 2}{40}) \cdot 10 = \frac{13}{40} \cdot 10 = \frac{13 \cdot 10}{40} = \frac{13 \cdot 10}{4 \cdot 10} = \frac{13}{4} = 3 \frac{1}{4}\) 4) \((\frac{3}{4} - \frac{1}{6}) \cdot 3 = (\frac{3 \cdot 3 - 1 \cdot 2}{12}) \cdot 3 = (\frac{9 - 2}{12}) \cdot 3 = \frac{7}{12} \cdot 3 = \frac{7 \cdot 3}{12} = \frac{7 \cdot 3}{3 \cdot 4} = \frac{7}{4} = 1 \frac{3}{4}\) Ответ: 1) \(3 \frac{3}{4}\); 2) \(4 \frac{2}{5}\); 3) \(3 \frac{1}{4}\); 4) \(1 \frac{3}{4}\)