Complex sentence: Feeney graduated from Elizabeth's St. Mary of the Assumption High School in 1949; he has credited his charitable spirit to his experiences at St. Mary and his 2016 donation of $250,000 was the largest in the school's history from a single contributor.
Split into simpler sentences: Feeney graduated from Elizabeth's St. Mary of the Assumption High School in 1949; he has credited his charitable spirit to his education at St. Mary. His 2016 donation of $250,000 was the largest in the school's history from a single contributor.