Complex sentence: First, the Board of Education decalred the property to be "surplus" in 1963, and in 1964 the County of Los Angeles Board of Supervisors rezoned the property to R-4, opening it up to high-density apartment use.
Split into simpler sentences: First, the Board of Education decalred the property to be "surplus" in 1963. Seconc, in 1964 the County of Los Angeles Board of Supervisors rezoned the property to R-4, opening it up to high-density apartment use.