Table: donnercoach_data
Columns: class_to_1928
class_from_1928
seats
quantity
year_s_of_manufacture
remarks

Question: What is the average quantity for coaches manufactured in 1921/23, and had 40 seats?
SQL: SELECT AVG("quantity") FROM donnercoach_data WHERE "year_s_of_manufacture" = '1921/23' AND "seats" = '40'

Question: Which class to 1928 value had years of manufacture of 1921/23 and class from 1928 of BCi-21?
SQL: SELECT "class_to_1928" FROM donnercoach_data WHERE "year_s_of_manufacture" = '1921/23' AND "class_from_1928" = 'bci-21'

Question: What is the smallest quantity having a Class to 1928 of BDi-21?
SQL: SELECT MIN("quantity") FROM donnercoach_data WHERE "class_to_1928" = 'bdi-21'

Question: Which class from 1928 had a class to 1928 of BDi-21?
SQL: SELECT "class_from_1928" FROM donnercoach_data WHERE "class_to_1928" = 'bdi-21'

Question: What were the remarks for the coach having a class from 1928 of Cid-21B?
SQL: SELECT "remarks" FROM donnercoach_data WHERE "class_from_1928" = 'cid-21b'