How many {place served by transport hub} are to/by {Buenos Aires} ?
How many transport hubs are there to Buenos Aires?
SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P931 wd:Q1486 }
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/P931> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q1486 .
} 

What is the number of transport hubs serving Buenos Aires?