The three offer curves viz., 0, 1, 2 of country cut the offer curve of  at points a, b, c which is equivalent to internatonal terms of trade as shown in the diagram below: From the above graph, it can be easily deduced that

International economics is concerned with the effects upon economic activity from international differences in productive resources and consumer preferences and the international institutions that affect them. Basicaly, International economics deals with issues arising from economic interaction among sovereign nations