б) 6 3/8 · 1 7/17 - 2 3/8 : 1 1/4 + 2/5

б) \( 6\frac{3}{8} \cdot 1\frac{7}{17} - 2\frac{3}{8} : 1\frac{1}{4} + \frac{2}{5} \)

1. \( 6\frac{3}{8} \cdot 1\frac{7}{17} = \frac{51}{8} \times \frac{24}{17} = \frac{3 \times 3}{1} = 9 \)
2. \( 2\frac{3}{8} : 1\frac{1}{4} = \frac{19}{8} : \frac{5}{4} = \frac{19}{8} \times \frac{4}{5} = \frac{19}{2 \times 5} = \frac{19}{10} = 1\frac{9}{10} \)
3. \( 9 - 1\frac{9}{10} = 9 - \frac{19}{10} = \frac{90}{10} - \frac{19}{10} = \frac{71}{10} = 7\frac{1}{10} \)
4. \( 7\frac{1}{10} + \frac{2}{5} = \frac{71}{10} + \frac{4}{10} = \frac{75}{10} = 7\frac{5}{10} = 7\frac{1}{2} \)

Ответ: 7 1/2.