Complex sentence: It is one of three active duty divisions in the Marine Corps, and together with the 1st Marine Aircraft Wing (1stMAW) and the 3rd Marine Logistics Group (3rdMLG) forms the 3rd Marine Expeditionary Force (III MEF).
Split into simpler sentences: It is one of three active duty divisions in the Marine Corps. The division, together with the 1st Marine Aircraft Wing (1stMAW) and the 3rd Marine Logistics Group (3rdMLG), form the 3rd Marine Expeditionary Force (III MEF).