\[\boxed{\mathbf{377}\mathbf{.}}\]
\[1)\ \frac{11}{21} < \frac{x}{21} < 1\]
\[\frac{11}{21} < \frac{x}{21} < \frac{21}{21}\]
\[x = 12;13;14;15;16;17;18;19;\]
\[20.\]
\[2)\ \frac{1}{4} < \frac{x}{28} < \frac{5}{14}\]
\[\frac{7}{28} < \frac{x}{28} < \frac{10}{28}\]
\[x = 8;9.\]