Complex sentence: During the 1970s and 1980s, as the economic situation in GDR worsened, many old buildings in city centre decayed, while the government fought against housing shortage by building large Plattenbau settlements in the periphery.
Split into simpler sentences: During the 1970s and 1980s, the economic situation in GDR decreased constantly. Many old buildings in city centre decayed, while the government fought against housing shortage by building large Plattenbau settlements in the periphery.