The answer is: Foreign policy leader
As a foreign policy leader, the president has the duty to establish agreement with another country that benefit our citizens the most.
The economic matters that the president discuss with another country would most likely related to international trade barriers, quota, or permit to open up new business in other country's territories. All of those are important to sustain united states' economy.
A treaty/International conventions in other countries. (Outside the US). Most treaties can be about land disputes, military issues, or even just trading.
Please post the paragraph for a full answer.
The democracy in Greece. Greek democracy is what most democracy in the modern world is based on.