The document presents a linear programming problem (LPP) case study about minimizing the daily costs of purchasing sand and gravel for a concrete company. The company produces 2000 tons of concrete per day using sand and gravel. Sand costs $6 per ton and gravel costs $8 per ton. The problem is formulated as an LPP model with the objective of minimizing costs and constraints for the total tons of sand and gravel purchased and limits on the percentage of each material used. Students are instructed to solve this case as a practice problem.