\[\boxed{\mathbf{786\ (}\mathbf{н}\mathbf{)}.\ Еуроки\ - \ ДЗ\ без\ мороки}\]
\[1)\ а)\ n < \frac{123}{30}\ \ \ при\ n = 4;\ \ \]
\[так\ как\ \ \frac{123}{30} = \frac{120 + 3}{30} = 4\frac{3}{30}.\]
\[\textbf{б)}\ n < \frac{198}{15}\ при\ n = 13;\ \ \]
\[так\ как\ \frac{198}{15} = \frac{195 + 3}{15} = 13\frac{3}{15}.\]
\[2)\ а)\ m > \frac{13}{5}\text{\ \ }при\ m = 3;\ \ \]
\[так\ как\ \ \ \frac{13}{5} = \frac{10 + 3}{5} = 2\frac{3}{5}.\]
\[\textbf{б)}\ \frac{275}{10} > m\ \ при\ m = 27;\ \ \]
\[так\ как\ \ \frac{275}{10} = \frac{270 + 5}{10} = 27\frac{5}{10}.\]