Student or Learner
I just read the following sentence and I was really confused of the using of "an".
Raising troop numbers by more than 20,000, including sending an extra 4,000 soldiers to the restive Anbar province.
I would have written: ......, including extra 4,000 soldiers ...... . If this would be wrong, could you please explain to me why?
Thanks a lot in advance,
an refers to AN EXTRA GROUP OF ...