П.78 Вычислите:

a) 0,46 \cdot \frac{3}{23} = \frac{46}{100} \cdot \frac{3}{23} = \frac{2 \cdot 23}{100} \cdot \frac{3}{23} = \frac{6}{100} = 0,06;
б) 5,53 : \frac{7}{9} = \frac{553}{100} \cdot \frac{9}{7} = \frac{79 \cdot 7}{100} \cdot \frac{9}{7} = \frac{711}{100} = 7,11;
в) \frac{5}{8} - 0,73 = 0,625 - 0,73 = -0,105;
г) 0,289 : \frac{17}{18} = \frac{289}{1000} \cdot \frac{18}{17} = \frac{17 \cdot 17}{1000} \cdot \frac{18}{17} = \frac{17 \cdot 18}{1000} = \frac{306}{1000} = 0,306;
д) 17,17 : 1\frac{5}{12} = 17,17 : \frac{17}{12} = \frac{1717}{100} \cdot \frac{12}{17} = \frac{101 \cdot 17}{100} \cdot \frac{12}{17} = \frac{101 \cdot 12}{100} = \frac{1212}{100} = 12,12;
е) 343,4 : 14\frac{3}{7} = \frac{3434}{10} : \frac{101}{7} = \frac{3434}{10} \cdot \frac{7}{101} = \frac{34 \cdot 101}{10} \cdot \frac{7}{101} = \frac{34 \cdot 7}{10} = \frac{238}{10} = 23,8.