suppose that before trade takes place, the united states is at a point on its ppc where it produces 20 loaves of bread and 20 units of steel. once trade becomes possible, the price of a unit of steel is 2 units of bread. in response, the united states moves along its ppc to a new point where it is producing 30 units of steel and 10 loaves of bread. is the country better off? how do you know?