The Kenya Agricultural Research Institute suggested to a farmer to spread out at least 4800 kg of a special phosphate and not less than 7200 kg of a nitrogen fertilizer to raise the productivity of crops in his fields. There are two sources to obtain these mixtures: A and B. Both are available in bags weighing 100 kg each and they cost 116 and 400 respectively. Mixture A contains these ingredients equivalent to 50 kg each. Determine how many bags of each type the farmer should buy in order to obtain the required fertilizer at minimum cost.