Complex sentence: She also exhibited paintings at the Long Bar and the Tiffin Room in the Hotel, and exhibiting Singapore art in countries like Bahrain, US and England, and notably became the first person to proudly declare that Singapore art were on par with "international standards".
Split into simpler sentences: She also exhibited Singapore art at the Long Bar and the Tiffin Room in the Hotel, and in countries like Bahrain, US and England. Della's reputation grew to be known as one of the first local art dealers who promoted Singapore art overseas, and to declare that Singapore art were on par with "international standards".