France will only specialize in schnitzel. Since for every bottle of wine not produced, France can produce 6 lbs of schnitzel, after specialization France now can produce 36 lbs of schnitzel. Similarly, Germany will specialize in wine and produce 6 bottles. Now suppose France trade 3 bottle of wine with Germany for schnitzels at the rate of 3 bottles of wine = 11 lbs of schnitzel, then Germany would receive 11 lbs of schnitzel and ships 3 bottles of wine to France. After the trade, France has 3 bottles of wine and (36 - 11) = 24 lbs of schnitzel. So France gains (24 - 18) = 6 lbs of schnitzel. Germany has (6 - 3) bottles of wine, as before, but now consumes (11 - 10 = 1) additional lb of schnitzel.

Now to understand the pattern of specialization, we need to determine the comparative advantage for each country. A country has an comparative advantage in producing a certain good if the opportunity cost (in terms of lost production of the other good) is lower. In this example, for every bottle of wine France produces, 6 lbs of schnitzel is lost. Germany, on the other hand, loses only (10 / 3 = 3.3) lbs of Schnitzel for every bottle of wine produces. Therefore, Germany has a lower opportunity cost of producing wine, and therefore has comparative advantage in producing Wine.

To see it differently, France has to lose (1 / 6) bottles of wine for every schnitzel produced. Germany, on the other hand, loses (3 / 10) bottles of wine for every schnitzel produced. So France has a lower opportunity cost of producing schnitzel and hence a comparative advantage in producing schnitzel.