A farmer has a supply of chemical fertilizer of type I which contains 10% nitrogen and 6% phosphoric acid and type II fertilizer which contains 5% of nitrogen and 10% phosphoric acid. After testing the soil conditions of a field, it is found that atleast 14kg of nitrogen and 14 kg of phosphoric acid is required for a good crop. The fertilizer type I costs Rs.2/kg and the type II costs Rs. 3/kg. How many kilograms of each fertilizer should be used to meet the requirement and the cost be minimum?