TASK DEFINITION: In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
PROBLEM: Who ruled Bithynia before Bas?, Context: The Bithynians were a Thracian people living in northwest Anatolia. After Alexander's conquests the region of Bithynia came under the rule of the native king Bas, who defeated Calas, a general of Alexander the Great, and maintained the independence of Bithynia. His son, Zipoetes I of Bithynia maintained this autonomy against Lysimachus and Seleucus I, and assumed the title of king (basileus) in 297 BCE. His son and successor, Nicomedes I, founded Nicomedia, which soon rose to great prosperity, and during his long reign (c. 278 – c. 255 BCE), as well as those of his successors, the kingdom of Bithynia held a considerable place among the minor monarchies of Anatolia. Nicomedes also invited the Celtic Galatians into Anatolia as mercenaries, and they later turned on his son Prusias I, who defeated them in battle. Their last king, Nicomedes IV, was unable to maintain himself against Mithridates VI of Pontus, and, after being restored to his throne by the Roman Senate, he bequeathed his kingdom by will to the Roman republic (74 BCE).

SOLUTION: Calas

PROBLEM: Frank Sinatra is an example of what genre of singer?, Context: Artists contributing to this format include mainly soft rock/pop singers such as, Andy Williams, Johnny Mathis, Nana Mouskouri, Celine Dion, Julio Iglesias, Frank Sinatra, Barry Manilow, Engelbert Humperdinck, and Marc Anthony.

SOLUTION: pop

PROBLEM: How many people in New York use a rail system for transportation?, Context: Mass transit in New York City, most of which runs 24 hours a day, accounts for one in every three users of mass transit in the United States, and two-thirds of the nation's rail riders live in the New York City Metropolitan Area.

SOLUTION:
two-thirds of the nation's rail riders