Ответ:
При \(n=3\): \(\frac3{14}-\frac13=\frac{9-14}{42}=-\frac5{42}\).
При \(n=6\): \(\frac6{14}-\frac16=\frac37-\frac16=\frac{18-7}{42}=\frac{11}{42}\).
При \(n=7\): \(\frac7{14}-\frac17=\frac12-\frac17=\frac5{14}\).
При \(n=3\): \(\frac3{14}-\frac13=\frac{9-14}{42}=-\frac5{42}\).
При \(n=6\): \(\frac6{14}-\frac16=\frac37-\frac16=\frac{18-7}{42}=\frac{11}{42}\).
При \(n=7\): \(\frac7{14}-\frac17=\frac12-\frac17=\frac5{14}\).