Ответ:

  1. \(6+4.8=10.8\).

  2. \((-6)\cdot0.12=-0.72\).

  3. \(1\frac{3}{8}-6\frac{2}{3}=\frac{11}{8}-\frac{20}{3}=\frac{33-160}{24}=-\frac{127}{24}=-5\frac{7}{24}\).

  4. \(\frac{8}{19}:(-4)=\frac{8}{19}\cdot\left(-\frac{1}{4}\right)=-\frac{2}{19}\).

  5. \(1.63+(3-2\frac{1}{2})=1.63+0.5=2.13\).

Ответ: 1) 10,8; 2) −0,72; 3) −5 7/24; 4) −2/19; 5) 2,13.