John Gill Commentary 1 Kings 22:42

"Jehoshaphat was thirty and five years old when he began to reign; and he reigned twenty and five years in Jerusalem. And his mother`s name was Azubah the daughter of Shilhi." — 1 Kings 22:42 (ASV)

Jehoshaphat was thirty five years old when he began to reign, and he reigned twenty and five years in Jerusalem So that he must be sixty years of age when he died:

and his mother's name was Azubah, the daughter of Shilhi but of what family they were is not said.