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A cement kiln with production capacity of 130 tons per day (24 hrs.) of clinker has at its burning zone about 45 tons of magnesite chrome bricks being replaced periodically, depending on some operational factors and the life of the bricks. If locally produced bricks cost P25,000 per ton and have a life of 4 months, while certain imported bricks costing P30,000 per ton and have a life of 6 months, determine the more economical bricks and by how much?