Question: How many former members from the band where Zack De La Rocha was a rapper/vocalist took part in the Audioslave discography? 
Sentence (from "Rage Against the Machine"): Formed in 1991, the group consists of rapper and vocalist Zack de la Rocha, bassist and backing vocalist Tim Commerford, guitarist Tom Morello, and drummer Brad Wilk.
Relevant evidence: Yes