A company produces three types of shoes, formal, casual, and athletic, at its two factories, Factory I and Factory II. Daily production of each factory for each type of shoe is listed below.

                Factory I       Factory II

Formal        100           100

Casual         100           200

Athletic         300          100

The company must produce at least 6000 pairs of formal shoes, 7500 pairs of casual shoes, and 9500 pairs of athletic shoes. If the cost of operating Factory I is 2000 per day and the cost of operating Factory II is 1900, how many days should each factory operate to complete the order at a minimum cost, and what is the minimum cost?