д) $$6\frac{3}{8}:1\frac{7}{17}-2\frac{3}{8}:1\frac{1}{4}+\frac{2}{5}= $$

д) $$6\frac{3}{8}:1\frac{7}{17}-2\frac{3}{8}:1\frac{1}{4}+\frac{2}{5}=\frac{51}{8}:\frac{24}{17}-\frac{19}{8}:\frac{5}{4}+\frac{2}{5}=\frac{51}{8}\cdot\frac{17}{24}-\frac{19}{8}\cdot\frac{4}{5}+\frac{2}{5}=\frac{51\cdot17}{8\cdot24}-\frac{19\cdot4}{8\cdot5}+\frac{2}{5}=\frac{867}{192}-\frac{76}{40}+\frac{2}{5}=\frac{289}{64}-\frac{19}{10}+\frac{2}{5}=\frac{289}{64}-\frac{19\cdot1}{10\cdot1}+\frac{2\cdot2}{5\cdot2}=\frac{289}{64}-\frac{19}{10}+\frac{4}{10}=\frac{289}{64}-\frac{15}{10}=\frac{289}{64}-\frac{3}{2}=\frac{289}{64}-\frac{3\cdot32}{2\cdot32}=\frac{289}{64}-\frac{96}{64}=\frac{193}{64}=3\frac{1}{64}$$

Ответ: $$3\frac{1}{64}$$