How many {crystal system} are to/by {amorphous solid} ?
An amorphous solid has how many crystal systems?
How many crystal systems are in an amorphous solid?
SELECT ( COUNT ( ?c ) AS ?d ) { ?c property:crystal_system resource:amorphous_solid }
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/P556> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q103382 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P556 wd:Q103382 }
23