The Uganda Farmers Research Institute suggested to a farmer spread out at least 4800 kg of special phosphate fertilizer and not less than 7200 kg of nitrogen fertilizer to raise the productivity of crops in his fields. There are two sources for obtaining these mixtures A and B. Both of these are available in bags weighing 100 kg each and they cost Sh. 40 and Sh 24 respectively. Mixture A contains phosphate and nitrogen equivalent of 20 kg and 80 kg respectively, while mixture B contains these ingredients equivalent of 50 kg each. Determine how many bags of each type the farmer should buy in order to obtain the required fertilizer at minimum cost.