$\frac{41}{1680}$ и $\frac{19}{720}$
$ \begin{array}{r|l} 1680 & 2\\ 840 & 2\\ 420 & 2\\ 210 & 2\\ 105 & 3\\ 35 & 5\\ 7 & 7\\ 1 & \end{array} $
$1680 = 2^4 * 3 * 5 * 7$

$ \begin{array}{r|l} 720 & 2\\ 360 & 2\\ 180 & 2\\ 90 & 2\\ 45 & 3\\ 15 & 3\\ 5 & 5\\ 1 & \end{array} $
$720 = 2^4 * 3^2 * 5$
$НОК(720; 1680) = 2^4 * 3^2 * 5 * 7 = 5040$
5040 : 1680 = 3
$\frac{41}{1680} = \frac{41 * 3}{1680 * 3} = \frac{123}{5040}$
5040 : 720 = 7
$\frac{19}{720} = \frac{19 * 7}{720 * 7} = \frac{133}{5040}$
$\frac{123}{5040} < \frac{131}{5040} < \frac{133}{5040}$, значит:
$\frac{41}{1680} < \frac{131}{5040} < \frac{19}{720}$.