Explain the Comparative Advantage Model of Trade (Including the Assumptions

Explain the comparative advantage model of trade (including the assumptions for the model) and how it is used to argue for free trade.
-Following are the production possibilities curves for the fictional nations of Bergsakeria and Solbergia showing their respective capacities for producing gizmos (G) and widgets (W). Use this information to answer the questions that follow.

a. Which nation has an absolute advantage in producing gizmos (and widgets for that matter)? Explain.
b. Which nation has a comparative advantage in producing gizmos? How do you know?
c. Which nation has a comparative advantage in producing widgets? Explain.