1. Найдите значение выражения: 1) (-12,4+8,9)-1\(\frac{3}{7}\); 2) \(2\frac{3}{8}-1\frac{5}{6}\)\(-1\frac{5}{8}\)

1) $$-12.4 + 8.9 - 1\frac{3}{7} = -3.5 - \frac{10}{7} = -\frac{35}{10} - \frac{10}{7} = -\frac{7}{2} - \frac{10}{7} = -\frac{49+20}{14} = -\frac{69}{14}$$.
2) $$(2\frac{3}{8}-1\frac{5}{6})(-1\frac{5}{8}) = (\frac{19}{8}-\frac{11}{6})(-\frac{13}{8}) = (\frac{57-44}{24})(-\frac{13}{8}) = \frac{13}{24} \times (-\frac{13}{8}) = -\frac{169}{192}$$.