Ответ:

  1. \(50 - 19{,}56 : (0{,}237 + 0{,}163) - 0{,}71 \cdot 0{,}5\)

    \(= 50 - 19{,}56 : 0{,}4 - 0{,}355\)

    \(= 50 - 48{,}9 - 0{,}355 = 0{,}745\).

    Ответ: 0,745.

  2. \(\left(3\frac{2}{3}+\frac{3}{4}\right):\left(6\frac{7}{12}-2\frac{1}{4}\right)\cdot 0{,}8\)

    \(= \frac{53}{12}:\frac{13}{3}\cdot\frac{4}{5}\)

    \(= \frac{53}{12}\cdot\frac{3}{13}\cdot\frac{4}{5}\)

    \(= \frac{53}{65}\).

    Ответ: \(\frac{53}{65}\).