Complex sentence: In November 2010, the Croatian Parliament decided to hold the EU accession referendum 30 days after the treaty was signed; since the treaty was signed on 9 December 2011, the referendum was consequently scheduled for 9 January 2012.
Split into simpler sentences: In November 2010, the Croatian Parliament decided to hold the EU accession referendum 30 days after the treaty was signed. Since the treaty was signed on 9 December 2011, the referendum was consequently scheduled for 9 January 2012.