A diet for a sick person must contain at least 4000 units of vitamins, 50 units of minerals and
1400 calories. Two foods A and B are available at a cost of Rs. 4 and Rs. 3 per unit,
respectively. If one unit of Food A contains 200 units of vitamins, 1 unit of mineral and 40
calories, and one unit of Food B contains 100 units of vitamins, 2 units of minerals and 40
calories. Find, by graphical method, what combination of foods A and B be used to minimise
the cost.