Complex sentence: He served as the Governor of the Brazilian state of Amazonas for two non-consecutive tenures: 1987 to April 2,1990, when he resigned from office to run for the Federal Senate.
Split into simpler sentences: He served as the Governor of the Brazilian state of Amazonas for two non-consecutive tenures. He first served as Governor from 1987 until April 2,1990, when he resigned from office to run for the Federal Senate.