в) -1 \frac{2}{15} + 3 \frac{5}{6} + (-1,7).

-1 \frac{2}{15} + 3 \frac{5}{6} + (-1,7) = -1 \frac{2}{15} + 3 \frac{5}{6} - 1 \frac{7}{10} = -1 \frac{4}{30} + 3 \frac{25}{30} - 1 \frac{21}{30} = 3 \frac{25}{30} - (1 \frac{4}{30} + 1 \frac{21}{30}) = 3 \frac{25}{30} - 2 \frac{25}{30} = 1