Complex sentence: Rhett is the official costumed mascot of the Boston University (BU) and the Boston University Academy (BUA) Terriers and has been the BU mascot since 1922.
Split into simpler sentences: Rhett is the official costumed mascot of the Boston University (BU) and the Boston University Academy (BUA) Terriers. The Boston Terrier has been the BU mascot since 1922.