CREATE TABLE table_15819 ("District" TEXT, "Counties Represented" TEXT, "Party" TEXT, "First Elected" FLOAT, "Committee" TEXT)

What counties represented have a democratic committee, and a committee of ways and means?
SELECT "Counties Represented" FROM table_15819 WHERE "Party" = 'democratic' AND "Committee" = 'ways and means'
SELECT "Counties Represented" FROM "table_15819" WHERE "Committee" = 'ways and means' AND "Party" = 'democratic'