Найдите значение выражения: а) (1 1/9 − 5 1/3) : (−1/5 + 2,1); б) (2/5 − 6,6) : (−1 1/4 − 1 1/3).

а) \(1\frac{1}{9}=\frac{10}{9}\), \(5\frac{1}{3}=\frac{16}{3}=\frac{48}{9}\), поэтому \(1\frac{1}{9}-5\frac{1}{3}=\frac{10}{9}-\frac{48}{9}=-\frac{38}{9}\).

\(-\frac{1}{5}+2.1=-0.2+2.1=1.9=\frac{19}{10}\).

\[\left(-\frac{38}{9}\right):\frac{19}{10}=-\frac{38}{9}\cdot\frac{10}{19}=-\frac{20}{9}.\]

Ответ: \(-\frac{20}{9}\).

б) \(\frac{2}{5}-6.6=0.4-6.6=-6.2=-\frac{31}{5}\).

\(-1\frac{1}{4}-1\frac{1}{3}=-\frac{5}{4}-\frac{4}{3}=-\frac{15}{12}-\frac{16}{12}=-\frac{31}{12}\).

\[\left(-\frac{31}{5}\right):\left(-\frac{31}{12}\right)=\left(-\frac{31}{5}\right)\cdot\left(-\frac{12}{31}\right)=\frac{12}{5}.\]

Ответ: \(\frac{12}{5}\).