Final answer:
The major petroleum-producing countries of the world in order from greatest amount to least amount are Saudi Arabia, Russia, and the United States.
Step-by-step explanation:
The major petroleum-producing countries of the world in order from greatest amount to least amount are Saudi Arabia, Russia, and the United States.
According to the provided information, about 80% of the world's readily-accessible oil reserves are located in the Middle East, with Saudi Arabia being one of the largest producers. Russia and the United States are also major oil-producing countries.