SELECT SUM(max_speed__km_h_) FROM table_name_22 WHERE quantity_built = "8+4" AND year_built < 1971
Berapa kecepatan maksimal unit dengan kuantitas 8+4 yang dibangun sebelum 1971?
CREATE TABLE table_name_22 (max_speed__km_h_ INTEGER, quantity_built VARCHAR, year_built VARCHAR)