Triangle $△JKL$ is similar to $△MNO$, with $J$ corresponding to $M$, $K$ to $N$, and $L$ to $O$. The length of each side of $△MNO$ is 2.5 times the length of its corresponding side in $△JKL$. The measure of side $JK$ is 12. What is the measure of side $MN$?