question: What is the set 2 the has 1 set of 21-25, and 4 sets of 25-20?
answer: SELECT set_2 FROM table_name_17 WHERE set_1 = "21-25" AND set_4 = "25-20"
context: CREATE TABLE table_name_17 (set_2 VARCHAR, set_1 VARCHAR, set_4 VARCHAR)