3) \(1,4a-\frac{51}{92}b+\frac{11}{25}c\), мұндағы \(a=\frac{25}{42};\ b=1\frac{6}{17};\ c=-1\frac{17}{33}\).

Запишем значения переменных в виде дробей:

\[1,4=\frac{7}{5},\quad 1\frac{6}{17}=\frac{23}{17},\quad -1\frac{17}{33}=-\frac{50}{33}\]

Подставим значения:

\[\frac{7}{5}\cdot\frac{25}{42}-\frac{51}{92}\cdot\frac{23}{17}+\frac{11}{25}\cdot\left(-\frac{50}{33}\right)\]

\[\frac{5}{6}-\frac{3}{4}-\frac{2}{3}=\frac{10}{12}-\frac{9}{12}-\frac{8}{12}=-\frac{7}{12}\]

Ответ: \(-\frac{7}{12}\).