63. Упростите выражение: 1) 2/15 * b + 3/12 * b - 7/20 * b; 2) 14 5/24 * a - 3 1/12 * a - 5 7/16 * a.

1) $$\frac{2}{15} b + \frac{3}{12} b - \frac{7}{20} b = \frac{2}{15} b + \frac{1}{4} b - \frac{7}{20} b = \frac{8}{60} b + \frac{15}{60} b - \frac{21}{60} b = \frac{8 + 15 - 21}{60} b = \frac{2}{60} b = \frac{1}{30} b$$

2) $$14\frac{5}{24} a - 3\frac{1}{12} a - 5\frac{7}{16} a = 14\frac{10}{48} a - 3\frac{4}{48} a - 5\frac{21}{48} a = (14 - 3 - 5)a + (\frac{10}{48} - \frac{4}{48} - \frac{21}{48}) a = 6a - \frac{15}{48} a = 6a - \frac{5}{16} a = 5a + a - \frac{5}{16} a = 5a + \frac{16}{16} a - \frac{5}{16} a = 5a + \frac{11}{16} a = 5\frac{11}{16} a$$

Ответ: 1) $$\frac{1}{30} b$$; 2) $$5\frac{11}{16} a$$