Ответ:

  1. \(−4.8+2.7=−2.1\).
  2. \(\frac{5}{6}−\left(−\frac{1}{3}\right)=\frac{5}{6}+\frac{2}{6}=\frac{7}{6}\).
  3. \(1.8\cdot\left(−\frac{5}{9}\right)+2=\frac{9}{5}\cdot\left(−\frac{5}{9}\right)+2=−1+2=1\).

Ответ: 1) −2,1; 2) 7/6; 3) 1.