12 When Arphaxad had lived 35 years, he became the father of Shelah.

Read Genesis 11:12 Using Other Translations

And Arphaxad lived five and thirty years, and begat Salah:
When Arpachshad had lived 35 years, he fathered Shelah.
When Arphaxad was 35 years old, he became the father of Shelah.