Ответ:

  1. 1)
    1. \(\frac{7}{16}\cdot\frac{8}{21}=\frac{1}{6}\).
    2. \(-\frac{5}{11}\cdot\frac{33}{65}=-\frac{3}{13}\).
  2. 2)
    1. \(3\frac{1}{4}\cdot3\frac{9}{13}=\frac{13}{4}\cdot\frac{48}{13}=12\).
    2. \(-5\frac{1}{3}\cdot1\frac{1}{2}=-\frac{16}{3}\cdot\frac{3}{2}=-8\).
  3. 3)
    1. \(\frac{5}{7}:\left(-\frac{10}{21}\right)=\frac{5}{7}\cdot\left(-\frac{21}{10}\right)=-\frac{3}{2}=-1\frac{1}{2}\).
    2. \(-\frac{4}{5}:\left(-1\frac{1}{15}\right)=-\frac{4}{5}:\left(-\frac{16}{15}\right)=\frac{3}{4}\).
  4. 4)
    1. \(\frac{5}{9}\cdot(-9)=-5\).
    2. \(-\frac{4}{5}:9=-\frac{4}{45}\).
  5. 5)
    1. \(6.5\cdot2.6=16.9\).
    2. \(-5.3\cdot7.7=-40.81\).
  6. 6)
    1. \(0.81:0.009=90\).
    2. \(0.1515:0.05=3.03\).

Ответ: 1) а) \(\frac{1}{6}\); б) \(-\frac{3}{13}\). 2) а) 12; б) −8. 3) а) \(-1\frac{1}{2}\); б) \(\frac{3}{4}\). 4) а) −5; б) \(-\frac{4}{45}\). 5) а) 16,9; б) −40,81. 6) а) 90; б) 3,03.