How many airlines have a hub at an airport run by LA World Airports?
SELECT DISTINCT COUNT(?uri) WHERE { ?x <http://dbpedia.org/ontology/operator> <http://dbpedia.org/resource/Los_Angeles_World_Airports> . ?uri <http://dbpedia.org/ontology/hubAirport> ?x  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Airline>}
Los_Angeles_World_Airports