How many {member of the crew of} are to/by {Enola Gay} ?
How many crew members work for Enola Gay?
how many crew members does enola gay have?
SELECT ( COUNT ( ?g ) AS ?x ) { ?g property:member_of_the_crew_of resource:Enola_Gay }
SELECT (COUNT(?sub) AS ?subs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?sub .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P5096> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q204424 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P5096 wd:Q204424 }
9