Suppose that before trade takes place, the United States is at a point on its PPC where

Question:

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?