Complex sentence: In mid- 1980s, Pakistan International Airlines played a large role in establishing the Emirates airline by providing technical and administrative assistance to the new carrier as well as leaseing a new Boeing 737--300 and an Airbus 300B4-200, both from Pakistan International Airlines.
Split into simpler sentences: In mid- 1980s, Pakistan International Airlines played a large role in establishing the Emirates airline. Also Emirates leased a new Boeing 737--300 and an Airbus 300B4-200, both from Pakistan International Airlines.