CREATE TABLE table_name_20 (name VARCHAR, mission VARCHAR, age_at_first_step VARCHAR)

Which astronaut went on the Apollo 16 mission at the age of 36y 6m 18d to step on the moon?
SELECT name FROM table_name_20 WHERE mission = "apollo 16" AND age_at_first_step = "36y 6m 18d"
SELECT "name" FROM "table_name_20" WHERE "36y 6m 18d" = "age_at_first_step" AND "apollo 16" = "mission"