11 15. (1--3)-4 16 8

$$ (1 \frac{11}{16} - 3 \frac{3}{8}) \cdot 4 = (\frac{1 \cdot 16 + 11}{16} - \frac{3 \cdot 8 + 3}{8}) \cdot 4 = (\frac{27}{16} - \frac{27}{8}) \cdot 4 = (\frac{27}{16} - \frac{27 \cdot 2}{8 \cdot 2}) \cdot 4 = (\frac{27}{16} - \frac{54}{16}) \cdot 4 = \frac{-27}{16} \cdot 4 = \frac{-27}{4} = -6,75$$

Ответ: -6,75