Ответ:

  1. \( -8.3+5.6-(-4.7)=-2.7+4.7=2 \).
  2. \( \left(-\frac{6}{8}\right)\cdot\frac{15}{16}=-\frac{3}{4}\cdot\frac{15}{16}=-\frac{45}{64} \).
  3. \( \left(-\frac{15}{32}\right):\left(-\frac{4}{7}\right)=\left(-\frac{15}{32}\right)\cdot\left(-\frac{7}{4}\right)=\frac{105}{128} \).

Ответ: а) 2; б) \(-\frac{45}{64}\); в) \(\frac{105}{128}\).