In this paper we solve a diet problem with the goal to find an optimal combination of food items on the condition that the daily nutritional requirements of a child are satisfied. The mathematical model of the problem is formulated as a linear program where the objective function is the number of calories for the proposed menu, on the condition that the constraints regarding the amounts of protein, fats, calcium, carbohydrates and dietary fibre consumed throughout an entire day are satisfied. We solve this problem by using the Solver tool in Microsoft Excel.