Найдите значение выражения: а) \(\left|-2\frac{3}{14}\right|+\left|-1\frac{5}{7}\right|-\left|-\frac{19}{21}\right|\); б) \(\left|2\frac{3}{14}-1\frac{5}{7}+\frac{19}{21}\right|\); в) \(-\left|-4\right|:\left|-1\frac{1}{3}\right|\).

а) \(\left|-2\frac{3}{14}\right|=2\frac{3}{14}\), \(\left|-1\frac{5}{7}\right|=1\frac{5}{7}\), \(\left|-\frac{19}{21}\right|=\frac{19}{21}\).

\[2\frac{3}{14}+1\frac{5}{7}-\frac{19}{21}=\frac{31}{14}+\frac{12}{7}-\frac{19}{21}=\frac{93+72-38}{42}=\frac{127}{42}=3\frac{1}{42}.\]

б) \[\left|2\frac{3}{14}-1\frac{5}{7}+\frac{19}{21}\right|=\left|\frac{31}{14}-\frac{12}{7}+\frac{19}{21}\right|=\left|\frac{93-72+38}{42}\right|=\frac{59}{42}=1\frac{17}{42}.\]

в) \[-\left|-4\right|:\left|-1\frac{1}{3}\right|=-4:\frac{4}{3}=-4\cdot\frac{3}{4}=-3.\]

Ответ: а) \(3\frac{1}{42}\); б) \(1\frac{17}{42}\); в) \(-3\).