How many {speaker} are to/by {Ronald Reagan} ?
What is the number of speeches performed by Rondal Reagan
How many speeches were done by Ronald Reagan?
SELECT ( COUNT ( ?v ) AS ?z ) { ?v property:speaker resource:Ronald_Reagan }
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/P823> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q9960 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P823 wd:Q9960 }
10