Short answers, pulled from the story.
H.L. Ahuja wrote that national output makes a country rich, not large amounts of money. This definition anchors the entire field of macroeconomics in tangible production rather than abstract currency figures.
Paul A. Samuelson and William D. Nordhaus defined output as goods or services produced within a given time period. The concept applies to any economic network, whether it is a single firm, an entire industry, or a whole nation.
An increase in labor usage pushes national output higher when more people work or work longer hours. Capital usage increases when businesses invest in new equipment or infrastructure to expand capacity. Effectiveness of factors of production rises through technological improvements or better management practices.
This identity means total national output equals total national income regardless of variable values because the output belongs to someone. Since output identically equals income, these components must balance perfectly in every accounting period.
Exports would be exactly equal to imports in both the countries under this scenario if the value of trades being made by both countries is equal at that point in time. This exchange mechanism allows different economies to specialize while still accessing goods they cannot produce efficiently themselves.