A company in the middle east delivers their packages to customers on camels and horses. A camel can carry 50 packages while a horse can carry 60 packages. A camel requires 20 units of food while a horse requires 30 units of food. The company needs to deliver at least 1000 packages and they have 450 units of food available. Since horses are not as suited for the hot climate, the number of horses cannot exceed the number of camels. How many of each animal should be used to minimize the total number of animals?