What is the total number of acres at Sai Tso Wan, opening before 1978?
CREATE TABLE table_name_29 (acres VARCHAR, landfill VARCHAR, opened VARCHAR)
SELECT COUNT(acres) FROM table_name_29 WHERE landfill = "sai tso wan" AND opened < 1978
### Context: CREATE TABLE table_name_29 (acres VARCHAR, landfill VARCHAR, opened VARCHAR) ### Question: What is the total number of acres at Sai Tso Wan, opening before 1978? ### Answer: SELECT COUNT(acres) FROM table_name_29 WHERE landfill = "sai tso wan" AND opened < 1978