A dietician wishes to mix two types of foods: 'Food I' and 'Food II' in such a way that the vitamins contents of the mixture contains atleast 8 units of vitamin A and 10 units of vitamin C. Food I contains 2 units/kg of vitamin A and one unit/kg of vitamin C. It costs ₹ 5 per kg to purchase Food I and ₹ 7 per kg to purchase Food II. He wishes to minimise the cost of the mixture. If x, y are quantities of Food I, II purchased, then the objective function is: