How many {base} are to/by {quadrilateral} ?
Bases in a quadrilateral?
How many bases does a quadrilateral have?
SELECT ( COUNT ( ?a ) AS ?u ) { ?a property:base resource:quadrilateral }
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/P3263> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q36810 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P3263 wd:Q36810 }
7