Ответ:

Спочатку треба знайти сумму [tex]\displaystyle-4\frac{5}{14}[/tex] i [tex]\displaystyle3\frac{5}{7}[/tex]

[tex]\displaystyle-4\frac{5}{14} + 3\frac{5}{7} = 3\frac{5}{7} - 4\frac{5}{14} = \frac{5+3*7}{7} - \frac{5+4*14}{14} = \frac{26}{7} - \frac{61}{14} = \frac{26*2}{7*2} - \frac{61*1}{14*1} = \frac{52}{14} - \frac{61}{14} = \frac{52-61}{14} = -\frac{9}{14}[/tex]

Тепер треба:

[tex]\displaystyle-\frac{9}{14} - 2\frac{8}{10} = -2 - \frac{9}{14} - \frac{8}{10} = -2 - \frac{9*5}{14*5} - \frac{8*7}{10*7} = -2-\frac{45}{70} - \frac{56}{70} = -2-\frac{45+56}{70} = -2-\frac{101}{70} = -2-\frac{1*70+31}{70} = -3\frac{31}{70}[/tex]