Two foods contain proteins, carbohydrates, and fats. Food A costs $1 per pound and contains 30% protein, 10% fat, and 50% carbohydrates. Food B costs $1.50 per pound and contains 20% protein, 4% fat, and 75% carbohydrates. What combination of these two foods provides at least 1 pound of protein, 2 1/2 pounds of carbohydrates, and 1/5 pound of fat at the lowest cost?