In Lima one worker can produce either 24 bushels of corn or 4 pounds
of tomatoes.
In Puma one worker can produce either 12 bushels of corn or 3 pounds
of tomatoes.
Lima's opportunity cost of producing 1 pound of tomatoes is
bushels of corn.
Puma's opportunity cost of producing 1 pound of tomatoes is
bushels of corn.
The country that specializes in producing tomatoes is willing to sell 1
pound of tomatoes in return for at least
bushels of
corn.
The other country will buy one pound of tomatoes but will not pay more
than
bushels of corn.