The problem can be described in algebraic form as follows.  The decision variables are the number of products of each type to build:  x1 for TV sets, x2 for stereos and x3 for speakers.  There is a fixed profit per unit for each product, so the objective function (the quantity we want to maximize) is:

Maximize     75 x1 + 50 x2 + 35 x3  (Profit)

Building each product requires a certain number of parts of each type.  For example, TV sets and stereos each require one chassis, but speakers don’t use one.  The number of parts used depends on the mix of products built (the left hand side of each constraint), and we have a limited number of parts of each type on hand (the corres­ponding constraint right hand side):

Subject to     1 x1 + 1 x2 + 0 x3 <= 400   (Chassis)
1 x1 + 0 x2 + 0 x3 <= 200   (LCD Screens)
2 x1 + 2 x2 + 1 x3 <= 800   (Speaker cones)
1 x1 + 1 x2 + 0 x3 <= 400   (Power supplies)
2 x1 + 1 x2 + 1 x3 <= 600   (Electronics)

Since the number of products built must be nonnegative, we also have the constraints x1, x2, x3 >= 0.  Note that terms like 0 x3 are included purely to show the structure of the model – they can be either omitted or included when entering formulas in Excel.