A farmer has a supply of chemical fertilizer of type A which contains 10% nitrogen and 6% phosphoric acid, and type B which contains 5% nitrogen and 10% phosphoric acid. After testing the soil conditions of the field, it was found that ateast 14 kg of nitrogen and 14 kg of phosphoric acid is required for producing a good crop. The fertilizer of type A costs Rs. 2 per kg and the type B costs Rs.3 per kg. How many kg of each type of the fertilizer should be used to meet the requirement at the minimum problem graphically.