CREATE TABLE table_203_7 (id DECIMAL, "pos." DECIMAL, "artist" TEXT, "single" TEXT, "year" DECIMAL, "sales" DECIMAL, "peak" DECIMAL)

how many more sales did elton john have than lou bega ?
SELECT (SELECT "sales" FROM table_203_7 WHERE "artist" = 'elton john') - (SELECT "sales" FROM table_203_7 WHERE "artist" = 'lou bega')
SELECT (SELECT "sales" FROM "table_203_7" WHERE "artist" = 'elton john') - (SELECT "sales" FROM "table_203_7" WHERE "artist" = 'lou bega')