Complex sentence: The national flag carrier and largest airline of Serbia, Air Serbia (former "Jat Airways"), uses Belgrade Nikola Tesla as their hub, it is also one of the operating bases for low cost airline Wizz Air.
Split into simpler sentences: The national flag carrier and largest airline of Serbia, Air Serbia (former "Jat Airways"), uses Belgrade Nikola Tesla as their hub. It is also one of the operating bases for low cost airline Wizz Air.