Unsaturated fatty acids are often classified according to the number of carbon atoms between the terminal methyl carbon (the omega carbon) and the closest double bond to the methyl end of the chain. an omega 6 fatty acid, for example, would have a double bond in positon 6 counting from the methyl end of the molecule.

classify,
gamma-linolenic, arachidonic acid, eicosapentaenoic acid(epa), palmitoleic acid, linoleic acid, oleic acid, and alpha-linolenic acid

into the following categories:
omega-3, omega-6, omega-7, or omega-9.