19. What do you mean by linear programming model? A person requires minimum 10, 12 and 12 units of chemicals A, B and C respectively. A liquid product contains 5, 2 and 1 units of A, B and C per jar. A dry product contains 1, 2 and 4 units of A, B and C per carton. If the liquid product costs Rs 30 per jar and dry product costs Rs 20 per carton. Formulate this problem in linear programming model. How many of each product should be purchased in order to minimize the cost to meet the requirements. Also find the minimum cost.​