4) (5/14 + 17/42) · 1 6/8

\(\frac{5}{14}+\frac{17}{42}=\frac{15}{42}+\frac{17}{42}=\frac{32}{42}=\frac{16}{21}\).

\(1\frac{6}{8}=\frac{7}{4}\), поэтому \(\frac{16}{21}\cdot\frac{7}{4}=\frac{4}{3}=1\frac{1}{3}\).

Ответ: \(1\frac{1}{3}\)