Question: How many teams were represented in the pair of motor races held on 18 and 19 April 2015 at the Bahrain International Circuit in Sakhir, Bahrain?
Sentence (from "2017 Bahrain FIA Formula 2 round"): It was the first round of the 2017 FIA Formula 2 Championship and was run in support of the 2017 Bahrain Grand Prix.
Relevant evidence: No