Cyclohexane and n-octane both are non-polar.
Hence,they mix completely in all preportions.
KCl is an ionic compound while n-octane is non-polar.Hence,KCl will not dissolve at all in n-octane.
$CH_3OH$ and $CH_3CN$ both are polar but $CH_3CN$ is less polar than $CH_3OH$.As the solvent is non-polar,$CH_3CN$ will dissolve more $CH_3OH$ in n-octane.
Thus,the order of solubility will be
$ KCl < CH_3OH < CH_3CN < $ Cyclohexane