CREATE TABLE table_203_249 (id DECIMAL, "position" DECIMAL, "song title" TEXT, "artist" TEXT, "sales" DECIMAL, "highest position" DECIMAL)

what is the difference between the sales of think twice and back for good ?
SELECT ABS((SELECT "sales" FROM table_203_249 WHERE "song title" = 'think twice') - (SELECT "sales" FROM table_203_249 WHERE "song title" = 'back for good'))
SELECT ABS((SELECT "sales" FROM "table_203_249" WHERE "song title" = 'think twice') - (SELECT "sales" FROM "table_203_249" WHERE "song title" = 'back for good'))