Complex sentence: Hong Kong and Macau are two cultural hub centers for Cantonese people, it is two of the top 50 richest international cities in the world, and also two of the highest GPD per capita in China.
Split into simpler sentences: Hong Kong and Macau are two cultural hub centers for Cantonese people, it is two of the top 50 richest international cities in the world. They are also two of the highest GPD per capita in China.