5.300. Найдите разность: a) 138 - 4; 6) 175-53; 9 14 7 в) 9-3.

a) $$13\frac{8}{9} - 4 = 13\frac{8}{9} - 4\frac{0}{9} = (13-4) + \frac{8-0}{9} = 9 + \frac{8}{9} = 9\frac{8}{9}$$

б) $$17\frac{5}{7} - 5\frac{3}{14} = 17\frac{5 \cdot 2}{7 \cdot 2} - 5\frac{3}{14} = 17\frac{10}{14} - 5\frac{3}{14} = (17 - 5) + \frac{10-3}{14} = 12 + \frac{7}{14} = 12\frac{1}{2}$$

в) $$9\frac{5}{7} - 3\frac{6}{7} = 8\frac{12}{7} - 3\frac{6}{7} = (8-3) + \frac{12-6}{7} = 5 + \frac{6}{7} = 5\frac{6}{7}$$

Ответ: a) $$9\frac{8}{9}$$; б) $$12\frac{1}{2}$$; в) $$5\frac{6}{7}$$