Đáp án:
$\frac{3}{5}$ :$\frac{5}{6}$ :$\frac{6}{7}$ :$\frac{7}{8}$+$\frac{2}{5}$+$\frac{23}{25}$= $\frac{3}{5}$ .$\frac{6}{5}$ .$\frac{7}{6}$ .$\frac{8}{7}$+$\frac{2}{5}$+$\frac{23}{25}$= $\frac{24}{25}$ + $\frac{2}{5}$+$\frac{23}{25}$=$\frac{2}{5}$+$\frac{47}{25}$=$\frac{57}{25}$