question: How many % of 1 Rep Max(Last Set) has a Set 4 of 145lb x 5reps?
answer: SELECT _percentage_of_1_rep_max_last_set_ FROM table_name_28 WHERE set_4 = "145lb x 5reps"
context: CREATE TABLE table_name_28 (_percentage_of_1_rep_max_last_set_ VARCHAR, set_4 VARCHAR)