Complex sentence: Ellis went on to college at Northwestern University to major in Industrial Engineering and obtain a master's in marketing where she also ran cross country and was a four-year letter-winner and NCAA qualifier for the NU swimming team.
Split into simpler sentences: Ellis went on to college at Northwestern University to major in industrial engineering and then obtain a master's degree in marketing. While at Northwestern she competed on the school's cross country team and was a four-year letter-winner and NCAA qualifier for the NU swimming team.