Complex sentence: He was president of Actors' Equity 1977 to 1982 in which office he supported human rights and had been president of the Associated Actors and Artistes of America since 1988.
Split into simpler sentences: He was president of Actors' Equity in the late 1970s and early 1980s, in which office he supported human rights. Bikel has been president of the Associated Actors and Artistes of America since 1988.