What's the number of users in the Nisibon-Yuma within the Del Este district?
create table table_20018310_1 (users___number_ varchar, irrigation_district varchar, juntas_de_regantes__wub_ varchar, PRIMARY KEY (users___number_))
select users___number_ from table_20018310_1 where irrigation_district = "del este" and juntas_de_regantes__wub_ = "nisibon-yuma"