Выполним действия по шагам:
$$6\frac{3}{14} + 1\frac{11}{14} = (6 + 1) + (\frac{3}{14} + \frac{11}{14}) = 7 + \frac{14}{14} = 7 + 1 = 8$$
$$4\frac{1}{4} - 2\frac{3}{4} = \frac{17}{4} - \frac{11}{4} = \frac{17 - 11}{4} = \frac{6}{4} = \frac{3}{2} = 1\frac{1}{2} = 1.5$$
$$20 : 8 = \frac{20}{8} = \frac{5}{2} = 2.5$$
$$1.5 \cdot 5 = 7.5$$
$$2.5 - 7.5 = -5$$
Ответ: -5