"The" and "plural"

[Nanatuha]

It's a sentence in my English textbook.

"You mean American football has the same rules as rugby?"

I can understand it's meaning, but I troubled that plural "rules" gather with "The".
Is there a case an article and a plural are existing at the some time? or merely mistake?

Thank you for advice.

[Tdol]

It's perfectly correct- you can use 'the' with a singular or a plural noun.

[Nanatuha]

I see. For some reason, I have misunderstood that "the" only can use for singular.
Thank you a lot.

[Tdol]

No problem.