Ответ:

1)

\(6,9-1,5=5,4\), поэтому \(\dfrac{5,4}{2,4}=\dfrac{9}{4}\).

\(\dfrac{19}{8}-\dfrac{11}{12}=\dfrac{57}{24}-\dfrac{22}{24}=\dfrac{35}{24}\).

Тогда \(\dfrac{9}{4}:\dfrac{35}{24}:\dfrac{5}{-18}=\dfrac{9}{4}\cdot\dfrac{24}{35}\cdot\dfrac{-18}{5}=-\dfrac{972}{175}\).

3)

\(1\dfrac{1}{3}=\dfrac{4}{3}\), а \(2,01=\dfrac{201}{100}\).

\(1\dfrac{1}{3}\cdot2,01=\dfrac{4}{3}\cdot\dfrac{201}{100}=\dfrac{67}{25}=2,68\).

\(3,25-2,68=0,57\).

\(13\dfrac{3}{4}-0,57=13,75-0,57=13,18\).

Ответ: 1) \(-\dfrac{972}{175}\); 3) \(13,18\).