A farmer has a supply of chemical fertilizer of type A which contains 10 % nitrogen and 6% phosphoric acis and type B fertilizer which contains 5% nitrogen and 10% phosphoric acid. After testing the soil condition of a field, it is found that at least 14 kg of nitrogen and 14 kg of phosphoric acid are required for a good crop. The fertilizer type A costs Rs 5 per kg and type B Rs 3 per kg. How many kilograms of each fertilizer should be used to meet the requirements and the cost be minimum? Using LPP, solve the above problem graphically.