Решение:

а) $$5\frac{5}{8} - 4\frac{71}{72} = 5\frac{45}{72} - 4\frac{71}{72} = 4\frac{117}{72} - 4\frac{71}{72} = \frac{46}{72} = \frac{23}{36}.$$

б) $$19\frac{17}{40} - 15\frac{83}{85} = 19\frac{17 \cdot 17}{40 \cdot 17} - 15\frac{83 \cdot 8}{85 \cdot 8} = 19\frac{289}{680} - 15\frac{664}{680} = 18\frac{969}{680} - 15\frac{664}{680} = 3\frac{305}{680} = 3\frac{61}{136}.$$

в) $$1 - \frac{3}{7} - \frac{6}{11} = \frac{77}{77} - \frac{33}{77} - \frac{42}{77} = \frac{77-33-42}{77} = \frac{2}{77}.$$

г) $$8 - \frac{11}{15} - \frac{14}{45} = 8 - \frac{33}{45} - \frac{14}{45} = 8 - \frac{33+14}{45} = 8 - \frac{47}{45} = 8 - 1\frac{2}{45} = 7\frac{45}{45} - 1\frac{2}{45} = 6\frac{43}{45}.$$

Ответ: а) $$\frac{23}{36};$$ б) $$3\frac{61}{136};$$ в) $$\frac{2}{77};$$ г) $$6\frac{43}{45}.$$