1. Calculate: $\frac{714285^{3}+285714^{3}}{714285^{3}+428571^{3}}=$
$\begin{array}{l}\text { II. 1. } \frac{7}{8} . \\ \text { Original expression }=\frac{(142857 \times 5)^{3}+(142857 \times 2)^{3}}{(142857 \times 5)^{3}+(142857 \times 3)^{3}} \\ =\frac{5^{3}+2^{3}}{5^{3}+3^{3}}=\frac{133}{152}=\frac{7}{8} .\end{array}$