Question: A firm produces two types of television set, an inexpensive type (A) and an expensive type (B). The firm earns a profit of 700 from each TV of type A, and 1000 for each TV of type B. There are three stages of the production process, each requiring its own specialized kind of labour. Stage I requires 3 units of labour on each set of type A and 5 units of labour on each set of type B. The total available quantity of labour for this stage is 3900. Stage II requires 1 unit of labour on each set of type A and 3 units on each set of type B. The total labour available for this stage is 2100 units. At stage III, 2 units of labour are needed for each type, and 2200 units of labour are available. How many TV sets of each type should the firm produce to maximize its profit?