Planning a Diet Paul's diet is to contain at least 24 units of carbohydrates and 16 units of protein. Food substance A costs $1.40 per unit and each unit contains 3 units of carbohydrates and 4 units of protein. Food substance B costs $0.90 per unit and each unit contains 2 units of carbohydrates and I unit of protein. How many units of each food substance should be purchased in order to minimize cost? What is the minimum cost? int: Define variables and write a system of inequalities to begin.