Complex sentence: He became a schoolteacher there at the age of 18, then graduated from Fairmont State Normal School (present-day Fairmont State University) and West Virginia University and remained in Morgantown, where he established a bookstore and stationery shop.
Split into simpler sentences: He became a schoolteacher there at the age of 18, then graduated from Fairmont State Normal School (present-day Fairmont State University) and West Virginia University. He then remained in Morgantown, where he established a bookstore and stationery shop.