John Gill Commentary 2 Kings 12:1

"In the seventh year of Jehu began Jehoash to reign; and he reigned forty years in Jerusalem: and his mother`s name was Zibiah of Beer-sheba." — 2 Kings 12:1 (ASV)

In the seventh year of Jehu Jehoash began to reign
So that he reigned twenty one or twenty two years contemporary with Jehu's reign, for Jehu reigned twenty eight years:

and forty years reigned he in Jerusalem ;
the same number of years David and Solomon reigned:

and his mother's name was Zibiah of Beersheba ;
a city in the tribe of Simeon, in the extreme part of the land of Canaan southward; her name in the Chaldee dialect is Tabitha, the same with Dorcas in Greek, (Acts 9:36) .