Total number of isomeric xylenes or dichlorobenzenes or cresols is

All the three are disubstituted benzenes, i.e., xylenes has two $\mathrm{CH}_3$ groups, dichlorobenzenes has two Cl atoms and cresol has one $\mathrm{CH}_3$ and one OH group.
Therefore, each one has three isomers i.e, $o-(1,2), m-(1,3)$ and $p-(1,4)$.