How old was Ahaziah when he began to reign?

22 years old

Two and twenty years old was Ahaziah when he began to reign. 2 Kings 8:26

42 years old

Forty and two years old was Ahaziah when he began to reign. 2 Chronicles 22:2

Note from The New Oxford Annotated Bible for 2 Chronicles 22:2: "Forty two is an error for "twenty-two"; compare 2 Kings 8.26."