Questionand more apples than oranges were purchased, how many pieces of each kind were bought? (39) Let $m, n \in \mathbf{Z}$ prove that $2 m+3 n$ is divisible by 17 if and only if $9 m+5 n$ is divisible by 17. (40) Find all $m \in N$ such that $m \mid n^{2}+1$ and $m \mid(n+1)^{2}+1$ for some