Ответ:

А) \(1-\frac{3}{8}\cdot3\frac{1}{5}=1-\frac{3}{8}\cdot\frac{16}{5}=1-\frac{6}{5}=-\frac{1}{5}\).

Б) \(\frac{1.9-9.1}{4.5}=\frac{-7.2}{4.5}=-1.6\).

В) \(1.6+2.38:1.4=1.6+1.7=3.3\).

Г) \(\frac{5}{21}:\frac{8}{7}-\frac{1}{12}=\frac{5}{21}\cdot\frac{7}{8}-\frac{1}{12}=\frac{5}{24}-\frac{2}{24}=\frac{3}{24}=\frac{1}{8}\).

Ответ: А) \(-\frac{1}{5}\); Б) \(-1,6\); В) \(3,3\); Г) \(\frac{1}{8}\).