Complex sentence: At age 17, Burns enrolled in Columbia University on a scholarship, where he worked in jobs ranging from postal clerk to dishwasher as a student and where he earned his B.A. and M.A. in 1925, graduating Phi Beta Kappa.
Split into simpler sentences: At age 17, Burns enrolled in Columbia University on a scholarship. During his time at Columbia, he worked in jobs ranging from postal clerk to dishwasher as a student before earning his B.A. and M.A. in 1925, graduating Phi Beta Kappa.