Complex sentence: Dr. Callahan earned her undergraudate degree at Loyola University Chicago and both her master's and Ph.D. degrees at Rush University in Chicago, where she served as an administrator at the university or at Rush University Medical Center for more than 25 years prior to coming to Marquette.
Split into simpler sentences: Dr. Callahan earned her undergraudate degree at Loyola University Chicago and both her master's and Ph.D. degrees at Rush University in Chicago. She served as an administrator at the university and at Rush University Medical Center for more than 25 years before going to Marquette.