Task: Text to Code
Input (English): Step 1: For each row in car_names table, find corresponding rows in model_list table and in cars_data table.
Step 2: find the average Maker in the results of step 1 whose Year less than 1980
Output (English): SELECT Avg ( T1.Maker ) FROM model_list AS T1 JOIN car_names AS T2 ON T1.Model = T2.Model JOIN cars_data AS T3 ON T2.MakeId = T3.Id WHERE T3.Year < 1980