Complex sentence: Kent lived much of his early life in and around New York City where he attended the Horace Mann School, and moved in his mid- 40s to an Adirondack farmstead that he called "Asgaard" where he lived and painted until his death.
Split into simpler sentences: Kent lived much of his early life in and around New York City where he attended the Horace Mann School. In his mid- 40s he moved to an Adirondack farmstead that he called "Asgaard" where he lived and painted until his death.