Complex sentence: Shanghai is a Chinese city located on the eastern coast of China where the Yangtze River flows into the East China Sea, and is the most populous city proper in the world, with a population of more than 24 million.
Split into simpler sentences: Shanghai is a Chinese city located on the eastern coast of China where the Yangtze River flows into the East China Sea. The city is the most populous city proper in the world, with a population of more than 24 million.