"The airline's proposed purchases of as many as 250 medium-range planes will probably be the basis of an overhaul of its routes; ..."
The sentence I post here is not underlined, so it should be correct.
However, the "it" in the end of the sentence seems to refer to "airline" . Otherwise, it may be illogical.
But in the Manhattan Prep book, this usage can't be correct because "XX's" is an adjective.
I am quite confused and look forward to the replay.