This is an either/or production, in that either Country A can produce 50 guns in a day or it can produce 100 pounds of butter in a day. But this isn't the only option for A, as they can also produce any mix of the two goods that still has the same proportion. For instance, Country A could produce as each of these good mixes represent the same tradeoff. But the numbers in the table represent the highest production combinations by one country. As you can see in the following tables, any other combination would result in each country producing less efficiently by not focusing on their most productive good.