EAST ORANGE, N.J. — Locally based brokerage firm Gebroe-Hammer Associates has negotiated the $5.1 million sale of a 42-unit apartment building in the Northern New Jersey community of East Orange. The historic building at 17 Summit St. was originally constructed in 1926 and offers 35 one-bedroom units and seven two-bedroom residences. David Oropeza of Gebroe-Hammer represented the seller, a limited liability company, in the transaction. Oropeza also procured the buyer, a private investor. Both parties requested anonymity.