To what does washington refer when he says “you have improved upon your first essay” in this excerpt from his “farewell address”?

Washington refer when he says"you have improved upon your first essay" is unity among nations and efficient management of common concerns.

Explanation:

He spoke about their independence, liberty, prosperity and unity among nations. He gave two advices during his farewell address they are the dangers related to partisonship, and foreign entanglements.

He warns against the long term foriegn alliances that might undertake the powers of the united states.

The main intension of Washington's farewell address is to serve as a guide for American public and his successors in office.

the answer is "by providing data about careers and annual mean wages"

porter is writing economic history because he is focusing on the cost of developing vaccines.