Complex sentence: There, she served as principal cellist of the Carnegie Mellon Philharmonic for four years, in addition to participating in several chamber orchestras, the Edgewood Symphony Orchestra and the Pittsburgh's Opera Theatre.
Split into simpler sentences: There, she served as principal cellist of the Carnegie Mellon Philharmonic for four years. She participates in several ensembles in the Pittsburgh area, such as the Edgewood Symphony Orchestra and the Pittsburgh's Opera Theatre.