Complex sentence: Young was a devoted lifelong member of her local and the national chapter of the NAACP, joining at the age of 12, serving nine years as both secretary and later president of the Wilmington, Delaware branch.
Split into simpler sentences: Young was a devoted lifelong member of her local and the national chapter of the NAACP. Joining at the age of 12, she served nine years as the secretary and later, she became the president of the Wilmington, Delaware branch.