Answer:
Ten pounds of chicken to trade for at least 40 pounds of vegetables but not more than 50 pounds of vegetables
Explanation:
         Vegetables     Chicken     Trade Off Ratio
John       40           10         4:1 (40/10) or 1:0.25 (10/40)
George      25            5         5:1 (25/5) or 1:0.20 (5/25)
John has comparative advantage in Chicken and George has comparative advantage in Veggies because :
So, Â John will sell Chicken to George & George will sell veggies to John. Gains from trade are when each get trade ratio better than their their own trade off ratio.