Give some stream of consciousness and then the answer. Hutch later co-wrote songs that were recorded by the Jackson 5 and their front man Michael Jackson, Smokey Robinson, the Miracles, and Marvin Gaye. In 1973, Hutch started recording albums for Motown, releasing the Fully Exposed album that year. That same year, Hutch recorded and produced the soundtrack to the Blaxploitation film, The Mack. Hutch had several R&B hits during this period, including "Brother's Gonna Work It Out" and "Slick". He also recorded the soundtrack for the 1974 film Foxy Brown. He recorded at least six albums for Motown, peaking with 1975's single "Love Power", which reached number 41 on the Billboard Hot 100. He left Motown in 1977 for Norman Whitfield's Whitfield Records.

Based on this passage, who sings brothers gonna work it out?
To answer this question, we should know that: Hutch had several R&B hits during this period, including "Brother's Gonna Work It Out" and "Slick".
Therefore, the answer is Hutch.