A company made up of three platoons. A platoon is divided into two sections. The Marines we saw operating in Aliens were one such section.Should the battalion commander want all of
the infantry companies dropped into a combat
zone along with their APCs, in a single assault,
nine of the dropships will be needed.
An M577 APC is designed to deploy one section, and a Cheyenne dropship holds one APC.
So you need two dropships and APCs to deploy a platoon.
Six APCs and dropships to deploy a company.
Eighteen dropships and APCs for three companies, or one battalion.
Did I misread or misremember and an APC can field a full platoon, not just a section? That would make the book's math right.