Complex sentence: Both of these businesses gradually flourished, and by the mid- 1970s, Berdella began working as a cook at several renowned Kansas City restaurants; also joining a local chefs' association, and helping establish a training program for aspiring chefs at a local community college.
Split into simpler sentences: Both of these businesses gradually flourished, and by the mid- 1970s, Berdella began working as a cook at several renowned Kansas City restaurants. He would also joined a local chefs' association, also helping establishing a training program for aspiring chefs at a community college.