з) -3 3/14 - (-2 5/6).

з) -3\(\frac{3}{14}\) - \(-2\frac{5}{6}\) = -3\(\frac{3}{14}\) + 2\(\frac{5}{6}\) = -3\(\frac{9}{42}\) + 2\(\frac{35}{42}\) = -1 + \(\frac{26}{42}\) = -\(\frac{42}{42}\) + \(\frac{26}{42}\) = -\(\frac{16}{42}\) = -\(\frac{8}{21}\). Приводим к общему знаменателю 42.