Complex sentence: He came to the United States in 1887 to work for the firm of Carrère and Hastings in New York City; both had been fellow students with Masqueray at the Ecole des Beaux Arts.
Split into simpler sentences: He came to the United States in 1887 to work for the firm of Carrère and Hastings in New York City. Both had been fellow students with Masqueray at the Ecole des Beaux Arts.