Complex sentence: On 27 June 2007, the governments of Singapore and Brunei celebrated the 40th anniversary of the Currency Interchangeability Agreement (since 12 June 1967) by issuing commemorative $20 notes, that are yellow, 149 × 72 mm in size, and made of polymer.
Split into simpler sentences: On 27 June 2007, Singapore and Brunei celebrated the 40th anniversary of the Currency Interchangeability Agreement (since 12 June 1967) with the joint-issue of the commemorative $20 notes. They are both yellow, 149 × 72 mm in size, and made of polymer.